There's nothing dangerous about it.

No Type-C receptacle featuring device can assume there will be no Vbus voltage on attachment from the other side, regardless of CC signals.

For a simple reason that USB C-A cable assemblies exist and can be plugged to any old charger or port on the A side, which will not wait or negotiate anything. It will just source Vbus 5V right away.

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crote 20 hours ago | parent [-]

... 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?

	▲	megous 3 hours ago \| parent [-]
		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.