Canonical content and AMP

At the F2F in March I was concerned that the best progressive web apps were
generally mobile-only, and I’m getting a similar feeling about AMP.

I’m wondering whether TAG have a view on the use of `m.` sites.  From an
architectural perspective `m.` is a bad thing, surely.  But I can’t build
my desktop webpages using AMP - because I would lose essential features
like reader comments, so I'm stuck serving (at least) two copies of the
same document.

HTML sandbox / Content Performance Policy seems like a better approach, but
I’m wondering whether I’m alone in thinking that a) technologies like AMP
can promote duplication of content in multiple formats in different
locations on the web, and 2) that’s a bad thing.

Seems to me that we've spent the last few years gradually moving away from
m., and we're now heading back towards that territory.  Is this a conscious
recognition that One-Responsive-To-Rule-Them-All was a bad idea?