I thought about this, and I think Stormblood's push towards forcing tanks and healers to play more defensively (particularly in regards to mobs smack us harder and the gated areas) is just messimg with some players in regards to old habits.
You can more easily spot tanks that never had to really mitigate too much and be cautious and healers that always had the burst behind them to easily weave in damage. Now the game is crunching them to be more watchful. It's not necessarily more difficult, just a shift in focus.
The good players are still going to be able to carry the bads. The tank that sees he needs to pop a self heal, the healer that just spam heals, or even a DPS doing some support.
It's just a shift.