I know couple of frameworks/systems support it, especially in php world.
Looks like that it's lost in layers - dev guys don't care much, sysadmins are sort of extincted, noone to bother to add Varnish into request processing queue. Needless to say, people ok HN even complain on Nginx configs,while for base caching it's much simpler, from my perspective.
Features like the memory governer [0], because trying to predict how much memory (open-source) Varnish will use is an absolute PITA and a sure-fire way to run out of memory if you're not careful.
My clients can't justify the commercial license costs (as a sibling comment says, CDNs eat Varnish's lunch in that market) and yet what I can do with Varnish and the power it gives me makes it real magic.
It would be nice to see a modern reimplementation of Varnish, open-sourced, but I doubt that would ever happen.
0. https://info.varnish-software.com/blog/two-minute-tech-tuesd...
But yes, Varnish Cache is not exactly what you would call Cloud Native.
Varnish Software have launched Pro currently on AWS only at a much lower price point, but it is still somewhat limited. I think that a Free-tier providing some of the goodies you mention would also cover much of what's needed for today's workloads including better memory management, in-core TLS and a better developer experience by having much better K8s support. Much of this could and should go into Varnish Cache, but that is a longer road as the project as such has a different focus than we do.
Expect more on that front this year @pbower :)