It’s because the process of picking a main can actually bring out a LOT of questions that people have, that aren’t easily answered, and most answers are subjective at best. In either case, if there were to be a stickied thread for how to pick a main, my answer remains the same.
Pick Ryu.
Just use a character you can implement basics with easily, like guile or balrog. You don’t necessarily have to keep using them forever, but it’ll help you get used to basic things like throw teching, blocking crossups, anti airing, using reversals when necessary etc.
Blanka has a step beast roll, slide, fireball proof ex beast rolls, in other words he’s not the easiest to zone. You’re just not using the tools you have for the right situation.