>>64479617 (OP)
I think a big part of the problem with these HK guns and a big reason why most countries have moved towards AR derivative platforms is modularity and ease of update/repair, especially out in the field or in less ideal environments.
Using any of the HK stamped guns as an example - let's say you get a squib and ring your barrel.
You need to punch the barrel pin out, press the barrel out of the rifle trunnion, press a new barrel in, verify the headspace is correct, drill and ream for a new barrel pin, press the barrel pin in place, press a new front sight on, and zero.
You're going to need a vice, punches, drill press or milling machine, accurate bits and headspace gauges, and a shop press to accomplish this repair AT MINIMUM, as well as someone experienced and competent enough to do the work in the first place.
For an AR derivative (again, at minimum), you're going to need a vice, a barrel nut wrench, and an allen hex key or punch to drive gas block pins out.
You're also not going to need an actual armorer or machinist, any ape with a couple braincells can watch a YouTube video and pull it off inside a half hour.
This ease of repair is largely because the barrel comes pre-headspaced.
If you're using a fixed FSB you're going to need a taper bit to drill new pin holes in the fresh barrel, and that's about the most complex operation.
This also assumes you're not just going to swap a fresh, spare upper onto your lower and instantly have an operating weapon again.
All of this obviously matters less of you're not in a combat situation and can readily spare the time and man hours to R&R, but it's still a line item cost you need to contend with.