No, I got multiple cases of managers with speech impediment, I also saw a blind tech lead and a deaf one (who also happened to have a small speech impediment).
I also saw a bunch of C-levels being total sociopaths but that's another story :)
I've worked with multiple blind coworkers and they were all amazing. They weren't amazing because they were blind, but they sure didn't let it slow them down.
I also saw a bunch of C-levels being total sociopaths but that's another story :)