I'm not sure why we're discussing Games For Windows Live. That thing wasn't really about account linking on steam it was shit a store, a bad launcher, trying to push paid online to PC.
Because GFWL required to have a Microsoft account which linked to other Microsoft services which to this day still work. FH5 didn't introduce this, GFWL did and there were a myriad of games that had this requirement so why would you expect FH5 to get review bombed when for one, it was there from the game's launch, and for two, dozens of games before it had the requirement. This meant most players already had an Xbox/Microsoft account anyway.
You're mostly listing people's gripes with launchers. people buying games on Steam in recent times have not had an issue at all with signing up to accounts to play their games as I said some have happily done so and bought games with the requirement. It was just funny to see that the same people who have happily signed up to accounts for other games throwing a fit now. Those who absolutely hate account sign ups on principle and wouldn't buy a game because of it (to request a refund) are different. I was referring to those who have happily signed up for accounts in the past now throwing a fit specifically.
Third-party accounts or launchers make no difference. The problem is the same; signing up for yet another service that may or may not be intrusive and players just aren't down with that. I've had a PSN account since 2007 so I don't really care but if I didn't, I'd get annoyed by having to sign up for another account. Steam, GOG, Ubisoft Connect, EA Play, Xbox Live, Battle.net, Epic, WOW, Square Enix, and I'm probably forgetting a few more. People just don't have patience for this, especially when it wasn't enforced but now is.