I don't recall ever seeing that legend on a piece of electrical service equipment. IME, instructions placed on such equipment are there for important reasons, typically the prevention of fire and/or electrocution hazards. Perhaps your experience differs.
Doesn't change the fact that it's a Code violation to install any piece of electrical equipment contrary to instructions.
So if the customer wants you to violate Code just to make it look nice, you go along with that?
In a typical consumer product, that's true. Electric service equipment is not a typical consumer product.
Of course not. Nice straw man, though.
You're getting rather far afield from the original topic. In case you've forgotten, that was installing service equipment in accordance with the manufacturer's installation instructions -- instructions which typically don't say anything at all about procedures for servicing branch circuits.
All of which is completely irrelevant to the question of whether the installer should follow, or ignore, the installation instructions.
It's a Code violation both in theory and in practice.
AFAIK, it's not a Code violation to do so.
Another straw man. Not a very good one, either.
Thank you -- that's exactly what I've been saying.