Because you don't get to dictate how a person chooses to spend their time. If this person is happy to do a project like this in Dreams then who are you to come along and piss all over it and criticize them for not using a more traditional engine? That has nothing to do with this thread being an "echo chamber of praise only" and more to do with people reacting to a poor comment that's not in good taste.
A real complaint would be critiquing the actual proficiency of the level/creation. Bitching about why someone spends their time creating in this game and should just move onto different pieces of software (which they may not even have access to) is asinine.
But sure, it's just an echo chamber.
Where did I dictate what the creator should do with his time?
Such false accusations, not cool.