A lot of manufacturers just don't do anything. At the same time I also wonder how real the damage is. I mean: I'm aware how the principle works and no doubt damage could be done, but I wonder how many people have had to replace speakers/headphones already after damage because of DC. Would be really interesting to find out.

In the old days, recording by microphones, which might not capable of picking up very low frequecies, but nowaday, due to digital mixing/manipulation, bad things can happen, RME is clever to apply the Digital DC protection, i.e. play safe.

Some elder people told me that vintage tube amp can damage speakers at the warm up duration, but I do not own a tube amp, no experience at all ..... and do not know if it is a myth or fact.

I had to replace a Sennheiser HD-800S driver that has been fried, literally, by DC.

Fortunately Sennheiser’s driver manufacturing is so astonishingly consistent that a single sided replacement ended up with two absolutely identical sides.

Not especially cheap, still.

The Sennheiser HD 800S is spec’ed with max. input of 0.5 W.
That is 12 V into it’s 300 Ohm - quite some.
Nevertheless it had been toasted, the Mylar diaphragm had melted, while the voice coil stayed intact.