You might recall the roller coaster that ensued when they thought it might be possible to reach heard immunity. The moment it became obvious that it wasn't going to happen, mostly due to an incredible lack of cooperation with everyone involved, they stopped talking about it. It was no longer valid, so why talk about it?

What backfired is not so much what the experts were saying, but how there was always an 'anti' chugging away at the press and online to make sure nobody knew what was what. We spend way too much time debunking crap info instead of just dealing with the good-at-the-time info provided by the experts.

They aren't hiding anything from the public. They just aren't planning on teaching the public absolutely everything about pandemics - just what is needed to be known at any given time. Otherwise you end up with too much information for anyone to even begin to understand what they need to do.

Telling people that some viruses eventually weaken has no benefit to anyone. The current virus isn't doing that, and raising hopes that it might is bound to give propagandists more fuel to work with.