And BU proponents are to blame, because they keep pushing it as "everybody sets their own limit and then magic happens (emergent consensus)".

If it follows the longest chain, then I believe the message of BU user can be summarized like this:

"I will accept any blocks the 51% of miners agreed on, at the expense of my business, which will now have to wait for something like an hour, before accepting any transactions".

This is how it should be promoted, then people would understand.

And this also begs the question: why the hell anybody needs to set their own limit at all?!

You still need a delay to see what size the miners picked, so your limit doesn't matter.