Don't you just hate it when someone sends you a brief text message and doesn't conclude with a full stop? No, of course you don't. You'd have to be a bit crazy to get even mildly irritated. Writing a text message is not the same thing as composing an essay, and if a text comprises a single sentence, or sentence fragment, there's really no point to the punctuation mark.
But here's the thing: I do get annoyed when the full stop isn't there. My very real reaction is the irrational product of a somewhat obsessive nature. However, I'm proud to say I've never expressed that ridiculous annoyance to anyone or sought to pontificate loftily on the issue, because I'm sane enough (I think) to know it just doesn't matter. What I've tried to do, over the years, is to turn that obsessiveness in useful directions for myself and others. When I'm writing I attempt to be meticulous. That doesn't mean mistakes don't get through - I'm well aware of their frequency, so please don't write to let me know about them - but I'm annoyed when they do and I do my darnedest to correct them and learn. When I'm looking at the writing of others in contexts in which being 'correct' is of some importance I attempt to help them towards a sense of what it takes to achieve that.
Sometimes your inner fascist can be your best friend. But only sometimes.