I think it’s better to have shoulder buttons in a fighter so you aren’t stuck with your right thumb doing everything. It’s not the default, but I usually use both bumpers and triggers for those inputs so the thumb it only responsible for two buttons.
The MegaDrive six button, which I guess you need for Street Fighter, also had that layout even before the Saturn.
I think it’s better to have shoulder buttons in a fighter so you aren’t stuck with your right thumb doing everything. It’s not the default, but I usually use both bumpers and triggers for those inputs so the thumb it only responsible for two buttons.
On a 3 button controller in Street Fighter, pressing start would switch your controls between punches and kicks.
I honestly forgot that the six button Mega Drive controller existed, but you’re right.