Never heard of this, doesn't make sense, and there's no constant evidence that backs this up, especially as
@osufeth24 for example is one person who waited plenty over 90 minutes with no delays. It would be one thing if it was reported that everyone was getting out of the queue prior to their estimated wait time (and prior to 90 minutes), but while a lot of guests are, a lot of guests are still waiting longer than that, whether delays are involved, or not. So, I cannot see this as happening, or at least it's not working if it is, unless it's a suggestion that they're tossing around and it's something they haven't implemented yet.
Also, I do not know about now, but when DD was first created, it had the longest queue in both parks. It would be an incredible waste to only allow the amount of people for a 90 wait in a queue that is designed still (I'm sure) to contain far more than that.