Yes, those hurdles of calculus are valid, and would need to be addressed. I do think, though, that since the “default” matchmaking seems to function reasonably well, the greater number of players and alliances that would prefer to always use their most powerful heroes in war would not likely cause too much ruckus.
Ultimately, this is just about variety within the bounds of most of the game’s mechanics, for me. Even if it were merely an optional event modeled after the raid tournaments, I’d have a blast with it – even with my blue-light bench! 