why are these forums unusable [title edited by moderator]

My recollection is that they did not say that all posts from prior to November 2016 would be lost/archived. They said that in most cases, they were archiving posts from before that. However, Adobe employees went through forums and selected older threads that had shown a lot of activity/views and those were also ported over. 

I believe they are rethinking some of that decision; the scripters, for example, are in an uproar over the inaccessibility of years of scripting information. In addition, we are supposedly able to request that specific archived threads be brought back, although how we're supposed to know which ones to ask for is vague, as well as the process of making the request itself.

Adobe seems to have ascribed to the old saying of, "there's never time to do it right, but there's always time to do it over." 

Although Adobe switched forum software the people that were selected, either hired specifically for this project or choosen from current staff, had and still have NO IDEA What they are doing.

Although other responder have said post from before 2016 have been lost that is totally false. I have seen and read post from back as far as 2009.

https://community.adobe.com/t5/Community-Help/About-the-Adobe-Forums-and-our-moderation-policy/td-p/2197757

That post is about the New forums, the old JIVE forums, from 2009.

So where is Mark Nichoson now? His last posts were in 2012.

https://community.adobe.com/t5/Back-Room/Did-I-click-a-Link-of-Doom/td-p/4154054

Although all of them only go back to 2009 and all seem to be in either the back room or the community help forums. But still the statement about everything before 2016 being lost is just a down right LIE.

This is a totally new forum platform, and there are problems which are being fixed

Messages from before 2016 were not moved from the old forum