Their flaw is that they don't release content to scale with how fast it is consumed. There is always a niche playerbase that will game and manipulate everything they get to complete it as fast as possible and then a month later start talking trash to SE that they need more to do and they're bored, and the development team will listen to them. They'll clear the new raid and have it on farm and rather than help a new player through they sell the clear, and so SE makes the next one harder. They'll blast through a 2000 light grind in like 2 days then want the next part of the quest, so the next part becomes a RNG grind with a gil sink attached. They'll manipulate a TT tournament to get 140k MGP and a rare card to get their stuff, and SE so far has turned a blind eye to it. The average player will never consume the content at the speed it is released in the time given, but the industry releases content based on the speed of the fastest players to complete it which will always be a detriment to the average playerbase.
How long term is acceptable? On an MMO anything released in a patch should be completable THAT patch. Then if you want to add more things to it, they should be acquirable in that patch they're released in as well. It shouldn't take 2 patches to outgear a raid to complete it, but that's happening a lot lately. It shouldn't take an expansion to get a Fenrir mount, but 1,000,000 is a LOT of MGP with no expediting mechanics. And it shouldn't take 3-4 months to knock out one chunk of the relic quest, but they added in so many gil sinks and RNG grinds that it took forever to get past the Atma phase for some players only to fall behind on a later step. Achievements like "Mountain out of Gil Hills", "Work Smarter, Not Harder", and "What Happens in the Saucer V" show that the GS was put in as some LONG, LONG term grind that immediately was a turn-off to me. Just "Mountain out of Gil Hills" is to earn 1,000,000 from the mini cactpot, which is winning 10k a day for 100 days straight IF you can even win 10k on your card. When 3.0 lands the last thing I want to do is ever have to go back to this place because I have to because I got screwed over every step of the way in a grind to get something released in February. The rewards are too good, and the prices are too high. Even for a vanity item
It's actually 0.01% since you can have 0000-9999 as one of 10k possible outcomes. 1% is 1/100, 0.1% is 1/1,000, 0.01% is 1/10,000.