These PF groups explicitly excluding jobs (not only MCH, but other jobs that are in need of some TLC from SE) are probably like those ilvl 315/three mistakes = kicked/one wipe = disband/high deeps/no baddies/pls skip soar groups that can't manage to get in a single clear, and clear parties fair better than them. I've been in Lakshmi groups with jobs like RDM, SAM, NIN, and MNK where I am pulling higher DPS on my BRD than them. I've also been in Susano groups with SMNs and BLMs doing very well in terms of DPS, sitting close to the top while also properly handling the mechanics.

Sadly, I can't speak much on MCH since I haven't seen many MCH in my groups (not from exclusion but I guess from where MCHs switched to other jobs after seeing how hard their job got screwed--I have encountered 2 so far in SB, one in V3.0 and the other in Bradam's Mettle).

I've never personally encountered any groups like this, but it's silly for people to exclude jobs based on things beyond their control. This isn't me saying MCH isn't in desperate need of some sort of rework, but just expressing the idiocy of assuming that a "meta" comp is the only decent comp to go with. Like I said, I've met SAMs and RDMs that barely pull over 2,000 DPS. I'm sure a skilled MCH could pull better than that, even with their design flaws.