I'm not against the idea per se, but "institutional investors are buying up homes" is an effect, not a cause. Boomers demanded that "house values are never allowed to go down, only up" and put all manner of construction-preventing policy in place to make sure this happened, so of course institutional investors showed up. If there's an asset class which is only allowed to go up, why wouldn't they?
Banning institutional investment doesn't remove the "can only go up" laws and mindset, so I think (assuming this even happens, which it probably won't: TACO) the actual effect on prices will be minimal.
I don't know if you've noticed, but politicians aren't in the business of root-cause analysis or actual solutions. They are in the business of making things either slightly better or significantly worse for certain people.
This would make the situation slightly better for people who want to buy houses.
Perhaps it's the case I'm 100% for this mainly because my extremely low expectations for politicians have been met and exceeded in this circumstance.
I don't know why we have to be negative about something that makes a small improvement in something that sucks.