What even is the purpose of all those non melee/blm jobs?

[Valence]

I didn't especially call for manasong to come back, although I definitely miss some of the old party resource support and synergy and deplore the focus on full individual teamplay besides damage raid buffs.

But to entertain the idea, what you describe is exactly what has been removed from HW/SB gameplay. You needed a rphys in party for manasong/tp song, but this was mostly a requirement for raids and long trials else you'd see people run out, or just stop attacking to preserve MP, especially those that didn't use Lucid in casual content. The resource paradigm was very different in that casters had a LOT more MP (healers 15k+) and spells used to cost less (except the resource hungry ones like AoE GCDs and AoE damage). So you could actually go on a good amount of time before running dry, but since the MP regen on the other hand was pretty low, you needed the manasong eventually. Also, the problem of relying too much on rphys jobs is why they added role actions like manashift on dps casters to actually single target MP regen as well, which was a boon in random content, but honestly, rarely required (and could be used for shenanigans like making bard's raid buff Foe Requiem be ready earlier since it was based on MP consumption, because yes, we also used to have interesting raid buffs mechanically back then not just a button you press every 2min, although radiant finale is a step in a good direction).

Now then, yes, you kinda needed manasong for serious fights (long trials and raids). The same way that even today you still need (kinda) to keep aggro as a tank. You also needed to control your own aggro as a DPS with specific abilities (for this one I'm not gonna say it was especially enjoyable having to press a button on cd to do just that, so I'm definitely not arguing to go back to everything we had, I'm just saying what we lost, and that left a big party synergy/support void). They chose to remove this because it was things that when not done properly by players, that tended to screw up the party in annoying ways, like having to ask for manasong in party chat once running dry because the bard/machinist didn't use it, or see a dps suddenly grabbing aggro because the tanks couldn't manage it properly.

If the idea is that people don't want to play team games with other players and don't want to feel bad because somebody else messed up, I guess we're more than halfway there today. The last thing remaining is to remove raid damage buffs, and also raid mechanics that can kill somebody else than oneself? Not sure how far into the rabbit hole we can go tbh.