Still not as bad as some analysis I saw like a year ago when they analysed 30 top grinders I think at plo 100 (not sure if it was stars and not sure it was plo 100) and only 3 of them were beating the game with wr bigger than 1bb/100....
Zoom is an absolute evil imo, the whole concept of zoom is that it basically decreases the edge of the regulars by not giving them chance to tableselect and use reads / stats and slightly increases the edge of the bad players by the things mentioned + tightening their range. So it pushes the game one step closer to the perfect scenario for stars where everyone is as close as possible to the BE line and they are printing money.
by playing zoom you agree that you are not able to tableselect and that the weaker part of the pool probably plays a bit tighter than in regular games. every reg playing zoom knows this and has to deal with this.
i'm not saying the rake is fair, imo it's in general too high, but i think the difference in winrates between zoom and reg tables is not stars fault.