I agree, for the artists that got unnecessary critiques in the past and that's important to not feel that burden early on specially when those rehearsals are meant to try things and fail at stuff, practicing, while Online Press take it as "the final staging" and judge it harshly.
BUT
I feel like all the rehearsals are part of the ESC experience and that's really what excites me the most in the contest, what they changed from the 1st to the 2nd to the final product. It's like a chunk of the contest that is not gonna be there anymore.
And I do think that sometimes bad critiques are an indicator that you're doing something wrong. If there is a general consensus about a dress being real ugly, or a staging that feels strange in its colors or i don't know ? the artist and the broadcaster will loose that precious feedback. How many times we saw something being modified because fans were saying that wasn't great and it turned out to be better at the end because of the feedback ? yeah sometimes fans are stupid and also gave stupid feedback but I do feel like most of the time the critiques were fair (the problem was how they were given : harsh and mean)