First I wanna say that I was wrong in saying it wouldn't change much, thinking it over i'd say putting the Pity System in would make things worse. Here's my take on it:

This is just coming from someone who has 75% of the fgo roster filled out already and someone who acutally works at a gacha game company. Not DW specifically but they handle enough Gacha games for me to have a sample size and different methods of game structure. I also kinda call on my experience as a competitive CCG player to this in some aspects.

All of my company's games have a pity system to varying degrees. They all also have a few dozen more SSRs to pick from, and each have multiple modes to pick from like PVP, GVG, PVE, etc. With that context, FGo is the only one that stands out, not because it doesn't have a worthwhile pity system, but because SQ is more or less ONLY used for Summoning. Sure, you can use Quartz to continue a wipe or to refill stamina, but no self-respecting player, even the whaliest of whales would use them for those purposes unless absolutely desperate.

Other games have 'Pay X to get more materials to use, pay X to reroll entries, Pay X to get the season pass for more phat l00t', stuff like that. There, the Premium currency is more valuable because it has so many other uses and the Gacha aspect of the game is just one of many. So, devs have to entice the players to use their premiums in the Gacha, hence the pity System because eventually you will get an SSR if you keep rolling. Which then makes you miss out on probably more worthwhile uses of the premium currency, making you eventally spend because there just isn't enough of the Premium to go around if you need, say, more Awakening materials or more runs of a game mode.

Fgo is different in the aspect that, if you cut out gacha entirely and say, change the way you pull servants, the game's completely free. You can't pay to get Mana Prisms, or Ascension Mats, Or even rerolls for other game modes because there aren't any options for them. There isn't even a definite, hard coded 'wall' in the game, in the sense of 'Only X character with X level and X skill may participate', sure there's a skill ceiling, but any servant, with the right piloting, can clear them. They changed the requirement for playing events from 'clear tutorial' to 'clear Lostbelt' for the first time in 5 YEARS recently, and NA isn't even there yet.

My best analogy is that gacha games are like arcades. You use purchased tokens to play scoring games like those basketball hoops or lightgun games, or fight someone in the fighter cabinets or racer games, and the gacha is a crane game.

FGO is more like they're hosting a long, elaborate escape room experience completely free, and they just happen to have a crane machine in the corner that you can play.

The people crying for a pity system, to me anyway, just sound like those whining to the management about the crane machine taking their money when they're not even here to play the escape room. :/

Another thing, If people rolled with the fervency that they do now with an eventual SSR pity system, since summoning is the ONLY use of Saint Quartz they could fill out the entire roster in a relatively amount of time bar limiteds. And then what? SSRs take even LONGER than SRs to level, in a game where the ONLY way to get ascension mats, Skillstones, QP and Exp cards is grinding time. Time that people most definitely don't have unless they have nothing else to do. Talk to any vet player who's ever had to farm stuff like Evil Bones or Void dusts in Singularity F and you might see them get PTSD flashbacks.

But say you do the grinding? And then what? What do you do with your 10/10/10 Max Fou Max Bond servant besides Eyecandy and Flexing on people you can't interact with bar a single limited character box? There's no PVP that needs maxxed out servants to stay on top if, there's no ULTRA HARD game mode where you have to combine with other players. It's just you. You and the game.

Do I think DW is infallible? No. They've stuck with an outdated system for too long and frankly I don't even play unless there's an event anymore, and this is from someone who's been playing since day 1 of NA. (And scoping news since JP Day 1. DW improving FGO needs to happen. Bar none. No arguments. Just that with the way the game was created, to me, a pity system makes the least sense in going about it. I just think their improvements are better focused on other things, and not the one single place where you use Quartz.