Banning stages was only really a necessity when there were excessively many stages that could "negatively" impact a match. If a Peach could counterpick both Brinstar and Mute City, that was regarded as "excessive." So a player gets a ban to avoid being counterpicked twice to stages which are heavily in their opponent's favor. It doesn't seem particularly necessary in the current ruleset. This doesn't mean I'm against it or anything. I just wouldn't make a fuss out of not having a stage ban, and I would be surprised anyone in favor of the MBR5 ruleset would make a fuss, since they are the ones who think these stages are "neutral" in the first place.
DSR is pointless in the current ruleset because it is a solution to a theoretical problem that will likely never actually occur when there are only six stages. There is a fear that an opponent would be able to win on exactly one stage, and only that stage. In my opinion, DSR only exists to combat that fear. But with only six stages, I think that fear is largely irrelevant.
I think, if you're going to scrub it out and have only five or six stages, you should just give each player a ban and be done with DSR. Though I think DSR without bans is equally valid. It's a matter of preference, largely. People are just entitled to being able to play the game they want, regardless of the desire of their opponent. They believe we should craft the ruleset in order to mitigate any advantage your opponent will ever have. It's rather silly.