I am more worried about some dedicated reddit, or 4chan user getting angry than the feds. I'm weird with this because when I write posts I wait 2 minutes, and think how would feds interpret my posts, and is it worth posting that.
I will most likely make a mistake with my anonymity one day, but to have alts increase anonymity wouldn't you have to be good at changing your writing style?
This is like my 7th account and I try not to tell the same story too often. Sure writing style matters but even just changing account names is pretty good. I mean if I was trying to find someone trying to analyze multiple random accounts for similarities beyond usernames is a huge effort. Which is the point. Make it harder for someone to find you but never assume it's impossible.
It's like putting a padlock on something. Sure it's not great but it might make it not worth the effort