tl;dr It's okay for moderators to wipe away comments and leave a conclusion (which they provide) and defer further discussion to meta. Often this will include comments they disagree with (and ones they agree with), and that's fine.
One of the recurring tasks for moderators is the need to clean up a huge chaotic discussion and leave behind a single conclusion. That is, moderators at some point have to make a decision and act; it can't always be discussed to death/consensus, especially not outside of meta.
There are of course gray areas sometimes. When the conclusion isn't entirely clear, moderators still have to pick one, at least for now. It can be further discussed later on meta, and decisions can be changed, but there's not always the luxury of leaving things there, starting a meta thread, waiting for a conclusion, and then going back - by that time you've left a mess in place for days. And it's also not moderators' job to start a meta post for every disagreement in which they're forced to intervene; that's something the rest of us can do too.
So I think broadly the right thing happened here: the comments disappeared, a possibly reasonable conclusion was posted, and there's even a "discuss further on meta" comment. We can debate about whether the conclusion was the right one in this case (in yet another meta question!) if we like, but I'm not too worried about what happened here. The absolute worst case is a moderator made an error in judgment about an honestly not that critical issue.
The sole issue I see here is that there's no short "here's roughly what was deleted and/or why" comment. I do think those are often a good idea, and would've helped a bit in these cases. That said, I don't think we should assume bad faith on the part of moderators: if they delete a discussion that we're all fully aware was too large (should've been on meta) and possibly less civil than ideal, and leave some sort of summary comment and a suggestion to discuss on meta, we can all read between the lines.
Remember, comments are temporary "post-it" notes. If we want a discussion to stay on the site permanently, we should move it to meta as soon as it becomes clear it won't be a simple, short back-and-forth. If we instead have a giant meta discussion in comments, we shouldn't be surprised if it gets wiped away, regardless of whether we happen to share the opinion of the moderator who leaves behind a "here's the deal for now" comment.