The whole concept has been back and forth…
Early DMP MVP - Wear it over the top. Includes, pockets, hood, and rank strap.
Logical - Keeps you dry.
Next DPM MVP - Wear it underneath. Includes hood and nothing else.
Also logical in another way - By the time you get your kit off and dig out your waterproof your smock might already be soaked. So get something dry next to you instead and get that wet smock on over the top. Also means that you’ve still got easy access to anything in your smock pockets.
Then they realised that few people were actually doing that and so it had just become an inconvenient outer garment - so redesigned again.
The MTP kit (in both heavy and light) is designed to permit wearing over the top. They have pockets/access and rank strap.
The idea of longevity seems to have long since fallen away.
Sure, worn over the top it will wear out more rapidly; but that’s next year’s budget…
It’s far more likely that the cheap zippers will fail before the fabric - hence the huge number of basically serviceable, but for the broken zips, jackets I see in the gash bins at stores.