Enforce Meta Gem Requirements has nothing to do with matching socket bonuses.
That is to say, checking the "Enforce Meta Gem Requirements" does not force *all* of your blue sockets to gems that would activate the blue socket for socket bonus.
The only thing that does for Metas is make sure that you have enough gems of the appropriate colors to activate your Meta.
If you meta needs 1 yellow, 1 red and 1 blue but your best dps gem is red and you would otherwise have all red gems, it will only replace enough of the reds to cover 1 yellow (either by a yellow itself or by a green or orange) and 1 blue (either by a blue,
green or purple gem) prismatic gems (NOT prismatic sockets) can also fulfill requirements (I think).
That said, since the optimizer needs to activate the Meta with a yellow and a blue, it will at least TRY to match up socket bonuses if they can give you a better total score. As an Arms Warrior, if I needed 1 yellow and 1 blue in addition to all my reds
to activate my meta, it would try and put them into sockets where the bonus would be +STR or +ArP, etc. as opposed to a socket where it's +Stam or +Hit (if I'm over the Hit cap).
The only other thing that it does is make it so you lose the effects of gems where their uniqueness has been violated, such as Nightmare Tear, which is Unique-Equipped. If you try to equip more than one, then it only counts one of them.