Depends on the context. On social media usually not, unless it's a thread about SPAG pedantry, in which case the likelihood of errors rises exponentially. 😀
At work- probably, not least because I have a reputation to maintain. I definitely correct documentation (and some will ask me to proofread it.)
I insisted on correcting a doc that was going to go round all UK employees earlier in the week - everyone else was saying it was really great, and I sent back a list of SPAG corrections, but there's no way I'd have been comfortable with it going out as was.
A lot of my colleagues have English as a second language, and we've had some great conversations about verb tenses and other things. But I have a British colleague who is not great at writing ("they was", for example,) and I find it much more of a struggle to find a tactful way of correcting her. I am half-tempted to say to our non-British tier 1 colleagues, if you're going to use anyone as an an example of how to write good English, please use someone else. But I haven't quite dared yet. I just offered to proofread stuff for anyone.
On OLD, I can let the odd typo go. But if they're really going to click with me, then the ability to write well is quite important, and if they can talk about etymology or the use of the subjunctive or something then they're really in with a chance. I'm getting enough matches that I can afford to be fussy. But then I have autocorrect to sabotage each carefully crafted sentence and put in words that don't exist in any known language, so it probably happens to everyone.