Reddit limits API usage mainly for IP, so you need multiple IPs to avoid this issue.
It's not impossible to have multiple instance of the same bot running in parallel, but there are too many race condition and it became too much to handle.
But then the onus is on Reddit to slacken these restrictions; WSB threads get 100K responses, which is the amount of engagement many social media can only dream of. If Reddit doesn't lift the limits and helps the WSB team out with moderation, they're shooting themselves in the foot because Reddit HAS to act if the WSB team can't moderate effectively.
It's why Twitter held off on banning Trump for so long; not so much because of public interest, but because Trump alone kept the platform up, running, active and profitable. Social media loves controversy like that.
All they had to do was set a higher minimum karma requirement to comment. Takes a few seconds to find and set that. They didn't have to shut the place down.
It's not impossible to have multiple instance of the same bot running in parallel, but there are too many race condition and it became too much to handle.