I didn't.

Neither a Hesco Barrier® nor an MRAP have much to do with field fortifications.

Which has little bearing on the fact that I do not agree with the excessive digging many advocate. There is a time and place and I've dug a hole or two in as hard a soil as anyone but excessive use is just like those Hescos and MRAPs -- it breeds an 'I'm safe here' mentality and a reluctance to move. In any serious war, one either moves or one dies.

That simple. This is true:
This mistake is probably part of the problem with modern field fortifications (the lack of experience after WW2 being the greater one).
You're also 100% correct on the marshaling areas. Which is one reason their use should be avoided where possible; they're necessary for marginally trained troops -- that mass Army thing again -- but not necessary for well trained units.