(In my experience) Most people type the way they speak and people who carefully articulate themselves are outliers. Grammatically correct written English is also very different from the spoken word.

I get what you’re trying to say. Unfortunately when the majority of what you’ve read is online is in spats of 150 characters or less (or whatever low character limit you’re working with) and an even more substantial amount of what you’ve written is within those constraints… On top of most of your interaction with the English language being incorrectly spoken English otherwise? It’s not hard to guess the end result.

This is something you can blame Twitter for. Blaming the user is odd, considering what they have to work with. Can’t blame people for communicating the way they know how.