I've seen some places advertise it but I have not tried it.

But, honestly, more generally in my head I wasn't thinking much about it since I consider that as a "cost optimization" thing than a "core kubernetes function." E.g. the addition (or not) of limits is just a couple lines, compared to all the rest of the stuff that I'd be managing specification of (replicas, environment, resource baseline, scheduling constraints, deployment mode...) that would translate seamlessly.

(And there are a lot of parts of kubernetes that annoy me, especially around the hoops it puts up to customize certain things if you reaalllly actually need to, but it would never cross my mind in a hundred years to characterize it as just a wrapper around cgroups etc like the OP.)