As always, METT-T determines application. Gross generalizations are just that-gross and generalized. Our own force commanders were begging for heavy armor in Mogadishu back 1994…and had to borrow from the Pakistanis IIRC. Plenty of examples in Iraq where mixed combat teams were integral to mission success-Fallujah, 2004 comes to mind.
Commanders need to display some elasticity with some of these "axioms" commonly tossed about.