This is incredibly shortsighted.
If you get Collective Shout to stop, another group might pick up where they left off.
The problem needs to be fixed, what you're suggesting is just making the people currently abusing it stop doing so. That's not a long term solution.
Symbol is better, as superscript isn't standard Markdown and isn't necessarily supported by other software than Lemmy. Mbin for example doesn't support it.
Not a reason not to use it of course, but it makes the symbol the more preferable choice.