The metas have always consisted of, 1 ranged 1 magical 2 melee, double support in one role would either make one outright win or make 2 ranged 1 magical 1 melee outright win
And given there’s more melee jobs then both other roles, statistically there’s more melee mains comparatively, excluding the fact SAM and DRG are prolly the most popular jobs in the game.
The options never reduced as the meta has never been changed really, its just the case that two support in one role would be very hard to put in a position where u neither stack them nor pick one over the other.
Again I’m not saying they made the right choice, nor am I agreeing with it’s turn out I merely am stating the likely reasons to why this has happened