You do that, and BRD and DNC become invalidated instantly, regardless of skill level. DNC may be
fine due to SAM/PCT but that's it.
This discussion already happened in Abyssos. The damage of "selfish" jobs depends entirely on themselves, and thus don't require others to perform well. They should still abuse the buffs of others for further increases, but they're not hindered by comp in the same way that buffing jobs can be (e. g. DNC's DP).
Imho, in the short term MCH would need to have a party buff. The long term solution would be to rework the ranged physical range role and/or not tie the strongest point of most jobs into the 120s burst window.