There is a wonderful page on Wikipedia which I came across for the first time a few days ago:

List of common English usage misconceptions | Wikipedia

Now, while it can just about get away with saying that something is not a mistake without inconsistency, it seems odd to then go on to claim that things are mistaken (e.g. the typography stuff) while maintaining from the outset that there aren’t actually any rules.

I reckon that my grammar/typography nazism is little more than a form of snobbery when it is directed at others. However, this is not to suggest that these things aren’t worth pursuing for oneself. Most grammatical rules do actually make writing better—aesthetically, and in how easy it is to understand—and being consistent is also a good idea to smooth things along. And typography is all designed to make things easier and/or pleasanter to read; serif vs. sans-serif is the best-known example of this but I imagine it applies to emdashes vs. hyphens too—although in this latter case I have seen cases where ambiguity has been resolved by the distinction. But suggesting that these things are anything more than a nicety is snobbery and I should get out of that habit.