God, I hate these posters so much.
TIER LISTS EXIST IN FIGHTING GAMES. I'M SORRY, BUT THAT'S JUST THE WAY IT IS.
Seriously, can you please just shut up? Obviously better characters are going to be seen more in tournaments, but that doesn't mean that other "lower tier" characters won't ever be seen in tournaments. For all we know, they can place reasonably well. It completely depends on who's playing them. Also, it doesn't matter if a character is low tier. If somebody loves to use that character, then nobodies stopping them.
Tier lists are just a way to see which characters are not necessarily "the best", but more so who has the most options, good match ups against the majority of the characters, and just who has the most potential as a character. Even so, I believe that all characters have tons of potential, just some do more than others.