Here is Annemarie Walop‘s second blog post.
While browsing on the internet a few weeks ago, I found a very interesting article on the website of Dutch quality newspaper De Volkskrant about the Dutch coordinating conjunction maar (“but”). The article is called ‘Beter: de maar-ziekte’ and it deals with the fact that maar is used increasingly often at the beginning of sentences, and that it suggests a contrast with the previous sentence.
Het [woord maar] wordt vaak ten onrechte gebruikt, wanneer de gebruiker een tegenstelling suggereert die er helemaal niet is. (It [the word maar] is often wrongly used, when the writer suggests a contrast that is not really there.)
The author of the article, Jean-Pierre Geelen, provides multiple examples of the wrong use of maar, and indeed, it can be found in virtually any book or article.

Jean-Pierre Geelen
Is the use of maar at the beginning of a sentence really een ziekte (“a disease”), as Geelen claims? Wikipedia seems to think so. It gives the following definition of a coordinating conjunction:
Een nevenschikkend voegwoord verbindt twee zinnen of deelzinnen die even belangrijk zijn… Een nevenschikkend voegwoord staat altijd tussen de deelzinnen in, nooit aan het begin. (A coordinating conjunction links two sentences or clauses of equal importance together… A coordinating conjunction is always placed in between the clauses, never at the beginning [of a sentence].)
Interestingly, Wikipedia gives no references to sources to back their claim. In the absence of a Dutch usage guide tradition, people would have to revert to Dutch books on grammar in order to find out whether it is acceptable to use a coordinating conjunction at the beginning of a sentence. Finding information on a usage item like this one is very time-consuming, especially if you take into consideration that the answer might not be in the grammar at all. Alternatively, you can try to find the item on the website of Genootschap Onze Taal (Dutch language society), which in this case states that en (“and”) and maar can be used at the beginning of a sentence, but the website does not include information on other coordinating conjunctions (for instance, it does not mention want (“for”/”because”).
What about English coordinating conjunctions, such as but, and, and for? Wikipedia states that “many students are taught that certain conjunctions … should not begin sentences. But authorities such as the Chicago Manual of Style state that this teaching has ‘no historical or grammatical foundation’”. (Notice the but starting the previous sentence!)

Wikipedia
The Chicago Manual of Style (2010) claims that “[i]n fact, a substantial percentage (often as many as 10 percent) of the sentences in first-rate writing begin with conjunctions. It has been so for centuries, and even the most conservative grammarians have followed this practice”. Even though the CMS claims that there is no usage dispute surrounding the use of a conjunction at the beginning of a sentence, some people still get quite worked up about it, as is apparent from the following quotation from Charles Allen Lloyd, author of We Who Speak English: and Our Ignorance of Our Mother Tongue (1938):
Next to the groundless notion that it is incorrect to end an English sentence with a preposition, perhaps the most wide-spread of the many false beliefs about the use of our language is the equally groundless notion that it is incorrect to begin one with “but” or “and”. As in the case of the superstition about the prepositional ending, no textbook supports it, but apparently about half of our teachers of English go out of their way to handicap their pupils by inculcating it. One cannot help wondering whether those who teach such a monstrous doctrine ever read any English themselves (1938: 257-8)
One of the most popular and best-known English usage guides, Fowler’s Modern English Usage (1996), says about and that “[t]here is a persistent belief that it is improper to begin a sentence with And, but this prohibition has been cheerfully ignored by standard authors from Anglo-Saxon times onwards’, and about but that ‘[t]he widespread public belief that But should not be used at the beginning of a sentence seems to be unshakeable. Yet it has no foundation” (1996: 52, 121). However, MEU writes that for “cannot normally be placed at the beginning of a sentence” (1996: 305).
In English, it seems as if there should not be any confusion: the coordinating conjunction is used at the beginning of a sentence by many people in many contexts, and prescriptivists do not find a problem with its usage as such. In The Netherlands we lack a usage guide tradition, so grammars are used as authorities on language use. Coordinating conjunctions are widely used by the public at the beginning of a sentence, but some people appear to have a problem with it. Perhaps it is time for a Dutch usage guide to be written, which has to include the disputed usage of coordinating conjunctions at the beginning of a sentence, among other things.
You repeatedly refer to the lack of a Dutch usage guide tradition. While the question whether or not the Dutch language area has a tradition similar to English is open for debate, there is in fact a strong language advice tradition in the Netherlands. The two biggest players are two websites: taaladvies.nl and onzetaal.nl/taaladvies. They both have interesting things to say about starting sentences with ‘maar’ and ‘en’, and they seem to agree with the English advice: it is perfectly fine to do it. See below for more details.
https://onzetaal.nl/taaladvies/advies/en-aan-het-begin-van-een-zin
http://taaladvies.net/taal/advies/vraag/1577/maar_aan_het_begin_van_de_zin/
You are right, of course! But are they usage guides in the sense of the English tradition? I know of only one actual book (see elsewhere on the blog), and that doesn’t seem to have been very popular. Nor was the Dutch version of Eats shoots and leaves. I really think the two traditions are significantly different.
Why would they not be usage guides? I would say that even these two websites can be included in the definition of usage guide: they meet all the criteria of Weiner (1988), such as focussing on only a small part of language, giving recommendations, and giving advice on all parts of the language. The only real difference with e.g. Fowler is the fact that this is an online source.
Interesting point: to us, in the project, usage guides are books. Which is not to deny that there aren’t any online fora (like Grammar Girl) that give usage advice.