An army is a tool for accomplishing goals in defence from and enactment of violence on actors of significant capability. Personnel are just one of the few raw resources said tool consumes. Conveniently said personnel can be used in place of other resources in this calculus but usually at significant inefficiencies. This can even mean that militaries with inflated personnel may even indicate that said military is lacking in other critical areas which must be plugged with disposable personel ie look at the Russian military and its meat wave attacks.