I'm not so sure. It might upset some people but I doubt it will really hurt them. We talked about going down next year, we decided it would be too crazy. But if we did, we would have at minimum done 3 days to see each park. My wife is a huge potter fan and it wasn't open when she went. The ony people I see getting really upset is the vloggers. And I wouldn't be all that concerned with them.
Realistically, if they do it right, they'll start selling the 3 or more day ticket bundles early. They'll sell enough to hit capacity and just say, sorry we have no availability for the park. Then technically they won't have to not sell single day. They just won't have any inventory left to sell single day. And if they don't sell to capacity, they can open up single day admission closer to opening.