I think the problem is that some folks seem to want a single fire-team model that does everything. I don't and I rejected it long ago.

I have concentrated on GPMGs with 1 gun in 3-5 man fire-team. That team is protected/Supported by 1-2 other teams with, with carbines/rifles only, and some HE Projection (RG, 40mm and maybe M-72A6-9).

basically a platoon has a mix of two types of team. The first type is "Recce/CQC" and the second type is stand-off fires, GPMG/Sniper team. Change emphasis and weapons mix, based on METT-C.

There is fairly substantial historical evidence that this works. We just choose to ignore it.