I think the gist was meant to be that, raidbuffers can outscale 'selfish' DPS atm, because the raidbuffs are multiplicative and balloon out of control balancewise. With this change, the idea (I think) is that to reach 'the maximum potential', raidbuffers need a Selfish to take advantage of their buffs, and Selfish's need Raidbuffers to push them to the next level, in a symbiotic relationship. In such a balance that you'd presumably want 2 of each for Savage and such. You could still throw whatever comp at EX trials and lower, but yeh. I assume the buffs would be more... integral? to the gameplay loop of these 'supports', rather than being almost an afterthought as they are now. You'd still have your Battle Voices and your Emboldens for 2min windows, but having gameplay more revolving around buffing allies more 'actively' I can see. Like, instead of BRD just getting 'play this song for your rotation and it happens to buff your allies', having the old songs back which restore MP, restore TP, apply Vuln (how we miss you, foe's requiem), and giving the class MP management to try and keep the Foe buff up as much as possible (perhaps by having your song procs trigger an MP restore effect, if only that was still tied to DOT ticks). RDM having to enchant allies with En-spells which also grant Black/White mana, so it doesn't throw out your rotation or stop you from using 'the cool zorro moves' as much, stuff like that
This would also necessitate another minirework to MCH to fully cement it as 'the selfish P-Ranged', likely by giving it cast times on it's multitool hits and buffing their potencies. Though, a 900p Chainsaw with a 1.5s cast time would probably feel pretty good, thinking about it, especially with Reassemble
IDK it's just kinda annoying seeing the same song and dance play out every tier, SAM is at the top of the charts because it's personal DPS is highest, everyone feeds it the gear in statics, then 10 weeks later once everyone has BIS it drops off the charts as 'raidbuff stacking' takes over and scales past it
I recall there being a massive outcry against the change to Mug/Trick, though that might be mostly because it was another 'make everything fit the 2min window' thing. I think NINs enjoyed their raidbuff being 1min, though that may also be a case of 'they enjoyed being meta for 'every raid tier since NIN was introduced', idk. Though you have to also remember that NIN did have utility in the past too, with Shadewalker and Smokescreen, Aggro manipulation tools. Aggro isn't exactly a thing now, but there can be room to give NIN some interesting thematic utility, like a buff to throw on tanks where the next X autoattacks are negated (they hit a shadowclone, or they do the log-substitute thing). I always felt like NIN was less 'direct' in it's damage thematically, rather working to sabotage the enemy, so maybe it's 'support' can be debuff themed, rather than 'buff ally' themed? Fair observation on MNK though
As for MCH, as funny as old Hypercharge was, it was also kinda just...there. It'd be like stapling a vuln onto Queen's Autoattacks. I feel like, as above, it'd be a better idea to just lean fully into MCH being, literally, 'the big guns' of P-Ranged and ramp their potencies up, with cast times to justify if needed. 900 might be too much, maybe 750 on AA/Drill/Chainsaw (since there's reassemble), and making Wildfire guaranteed to Crit/DirectHit (and therefore also able to scale off of Crit/Dhit increases like Battle Voice/Battle Litany)