Neptune, what I'm seeing is a lot of kicking and screaming just because people on the Internet disagree with you. This is not a particularly effective way to convey your point. However, I think the root of your argument regarding Darkhold class bias is fundamentally flawed. MP management was never the issue in Darkhold. The issue was that boss mechanics (namely, the AOEs) were presented that could either be brute forced or completely ignored. You can brute force it by stacking healers as you suggest, or you can ignore it by using ranged DPS. Both encourage class bias, but since we're talking "4 healers" and MP management issues, I assume we're talking about brute force healing through AOEs.

The entirety of the problem actually lies in the fact that you can fill half your party with healers and win in the first place. This is an encounter design issue, and is not in actuality an MP management issue at all. If the encounter was tuned so that you could not afford losing those DPS slots for extra healers, groups would be forced to either switch to ranged DPS or learn how to deal with the AOE mechanics "properly". Of course, the ranged DPS issue is another big flaw with the encounter design, but that's another issue entirely unrelated to MP management. Either way it is unsatisfactory to "solve" the problem by reverting to pre-1.18 style heal-bombing when the MP is not the core issue.