I am horrible at commas. I sometimes just put them where it sounds good. I have always thought that I was pretty good at English. I have a decent vocabulary and such, but I just cannot do commas to save my life.
I mean on the internet it really doesn’t matter. As long as you use something to break up and explain long trails of thought so that it is legible - no one really minds. The only thing that really bothers me is when people write really long walls of text where there is no spacing at all. I often just don’t bother reading it at all because it takes too long to decipher.
You are probably right there that no one on the internet cares. Actually, I think the internet is probably part of the problem. If you spend 30 years on the internet typing however you choose, you may tend to forget the punctuation lessons you learned in school. Or at minimum, be unsure of them.