Its funny, this game is one of the few that kinda keeps whales in check. You get all these awesome servants and CE, then you're hamstrung into using lower tier servants and high cost CE from events every time. This is why I'll probably never grail a 5* servant.
Preface: Sorry for the wall of text, but I like talking about game balance.
Rather than keeping whales in check, it's more that they keep the game playable to everyone (well, more or less) They may seem similar, but there's a huge difference.
I'm referring to other games here, but over time, I've realized that the best way to balance things isn't to avoid OP characters or even deliberately produce OP characters. It's to make sure that you avoid useless units. The first game that made me realize this was Super Robot Wars (specifically Z series). They balanced the game on the grounds that you won't upgrade your units. This resulted into a game where you can generally use your fave mecha to do a lot of things.
(SRW V shifted things a bit in a bad way. Not sure about SRW X yet).
A more recent example would be SaGa: Scarlet Grace. (You should buy it if you're interested in a unique RPG). One of the selectable characters, Urpina, gets a certain otherwise-hard-to-get "weapon type" through a story quest. This weapon type basically removes all her weakness (aside from poor resistance from stat effects). It provided extremely good offense, decent defense, extreme versatility, and yet, it didn't invalidate other weapon-types. It felt good using other people not named Urpina.
Of course, FGO could still use better balancing, but it's far better than many other games out there.
I'm trying to play some more phone games right now (SRW X-Omega, Makai Wars, Love Live, Senran Kagura Shinobi Master). X-Omega, I am playing seriously for the past 2 weeks, and it is THE very definition of "keeping whales in check". Remember how we can more or less clean the shop with only the event Servant and borrowing from friends? I'm barely at 10% of cleaning the shop in this game because I don't have the current gacha characters. And that's with diligent playing.
I'd be lying if I say that I am not a bit concerned about FGO's future policies/guidelines. A few months ago, FGO got a new(?) "development director" for Part 2 (Kanou Yoshiki). Word is that he is to blame for Border Break's massive power creep.
I didn't know anything about FGO's devs, and I'm still *trying* to get more info on them. Especially why everyone hates Shiokawa (FGO Creative Director; joined DW in 2016) and Shouji Akihito (Delight Works president). I honestly don't want to scrape 2ch or twitter of whatever, though.
As far as Shouji goes, the hate seems to be primarily due to bugs, overlapping maintenance and dev oversights in the game, with the most famous one being: save data was in the cached data of the phone. Most of them were fixed eventually (which, IMO, is the important part).
I'm still confused whether he's still directly involved in FGO (some info says he's no longer FGO's runner since 2016?)
But honestly, I probably won't be playing now if not for him. An excerpt from the nicovideo entry above (using my shitty translation skills):
Through the intermediation of a common friend, TYPEMOON's Takeuchi consulted Shouji regarding a Fate RPG for smartphone. This eventually led to his involvement in the development and operation of Fate/Grand Order. The Basic Design of FGO did not include any elements that the users will not be able to clear if they don't put money in. He thought that the users should be the ones to put the price on the value they offer.
I'm hoping that whoever is at the helm, this would hold true. I'd be more willing to put money into the game than otherwise.
Edit: 4* and below aren't worth grailing past 90 either. The cost-return is too minimal.
