Lock out is to heavy handed

[NyarukoW]

... if they tweaked it to where it wasn't inflicted on people who make fully premade groups, since they're not hurting anyone when/if they withdraw.

Pre-made full parties don't get penalty. See:
forum.square-enix.com/ffxiv/threads/201200-Locked-out-of-the-Duty-Finder.?p=2550731#post2550731

.. This excludes times when you queue as a complete pre-made party. Withdrawing in these instances will not count towards the penalty.

*When it comes to Crystal Tower, immunity for the withdrawal penalty only takes place when you queue as a full, pre-made 24-person alliance.

And the penalty is too light. People are doing the withdraw too casually already. It is 3 strikes and then just 30 minute penalty. That is too easy to shrug off. This is NOT heavy handed at all. The collective punishment will have players help reinforce the notion that it is not okay just to withdraw and help instill better habits. This is a good thing. You don't get to turn a blind eye or deaf ear to your friends behaving badly.