... which is exactly why a source with a female USB-C port is not supposed to apply VBUS until it detects a sink.

Obvious counterpoint: what's going to happen when two noncompliant "always provide 5V" USB-C wall warts are connected together with a C-C cable? How well does a charger like power being fed into it?

Nothing will happen most of the time. Cheapo chargers are usually flyback design which is immune to this.

Anyway if you connect anything non-compliant together anything can happen. My point was that always on 5V is no problem for compliant device on the other side.

Normal people don't connect two chargers together. :) You can create all kind of fun combos though. Like connecting your PC via USB-A port to a type-c charger, etc. It's all by design safe. USB-A will provide power no matter what, it doesn't matter what CC signals are.