AvaricePanda
Smash Lord
You're assuming that the people have to do an attack right as the spotdodge becomes vulnerable, which is wrong, because if you spotdodge and you're opponents in a state where he can do anything, he can just use his attack a few frames before the spotdodge vulnerability. It takes timing but it's not difficult. In this case, Sonic's easiest move to punish a spotdodge is F-air since the hitbox is out longer and it covers that distance well.
Most beginning players get in a habit of spotdodging and rolling too much and work their way to doing it less. It is quite punishable; I've shown you on paper, me as well as a lot of people (including those that you play with) have punished many spotdodges in person. At top level of play there isn't an abundance of spotdodges, and it's safe to assume because they know much more about the game's mechanics than most do and still don't abuse spotdodging, it's because it's not as good as you're making it out to be.
Most beginning players get in a habit of spotdodging and rolling too much and work their way to doing it less. It is quite punishable; I've shown you on paper, me as well as a lot of people (including those that you play with) have punished many spotdodges in person. At top level of play there isn't an abundance of spotdodges, and it's safe to assume because they know much more about the game's mechanics than most do and still don't abuse spotdodging, it's because it's not as good as you're making it out to be.