I don't think we need a strict trinity 2/2/4 system where jobs can only do one set thing based on their role type, a extreme example would be that healers/tanks do 10% of a dps damage, healers only heal, tanks only mitigate I think this would be a very boring and bland system.

But I think if you can have "funny" no healer runs I do believe the reverse of no tank runs should be achievable (no dps is also a thing that happens depending on the checks), giving healers strong single target mits, more damage buttons that comes with more damage (equal to tank), even some sort of way to increase aggro by giving someone a temp increase of something I'd see as fair. (could be used for trolling lol, similar to rescue)

I personally dislike a riggid 2/2/4 system, as for me it heavily limits what a role can do based off class type. I personally enjoy support and even limited healing on tanks.