I would like to also support this idea.

There comes a point where you know you can fight Lilith a thousand times without losing once, but you don't know if you're going to see a single meaningful reward for it. Giving out points toward progression, but scaling it to difficulty, would allow for a tangible sense of progress from your fights, rather than just banging your head against a wall and hoping something falls from it.

I feel like asking someone to repeat a fight five hundred times for their drop is a lot, though. On all but Shinryu, it seems like equipment drops somewhere around one time in fifty to one time in a hundred, on Very Easy. Not necessarily the equipment you want, but something nonetheless. It seems fair to try to aim for roughly the same rate of item generation.

Maybe have a target of 10000 points for a piece of equipment, with each fight giving out a fixed 100 points on Very Easy, divided evenly among party members? Then you get a party needing to do the fight six hundred times, to get six pieces of equipment, or a solo participant doing the fight one hundred times to get one piece. This would discourage partying to a certain extent, but parties could potentially be doing higher-level fights to get 200, 400, or up to 1600 total points (266 per person) on Very Difficult, which could compensate.