They have started to integrate GitHub accounts into stuff, which for the services that support it are an improvement, but its now yet another login to the fray.
There were some really weird loop login situations you just could not break - perhaps in part due to account type confusion or an existing login or legacy account stuff on old accounts.
I was an early Microsoft Passport user, not sure if that's hung around as well.
In fairness the google home user vs apps user distinction is also annoying (can't share google home control with various google account types etc).
That said I really, really dislike login practices that require me to relogin after certain time. When did anyone had to relogin into gmail? Why all other services keep expiring their logins?
But on the flipside, the infinite session might not be a benefit in the long term. A user who signs in just once when creating account will have no idea of how to log in. They'll have forgotten their password because they only used it the once, they've lost access to their recovery email account due to changing jobs, etc. And while any single one of these issues would have been trivial to fix if noticed quickly, letting them pile up for a year means you might have very few ways of proving it really is you when that nominally infinite session finally gets killed for some reason.
I very nearly had this happen last month. I had been intending to close an old phone number from a different country, where I haven't lived in 15 years. But I also happened to try to log into a PSN account for the first time in years (consoles basically never require new logins); the password mysteriously did not match the one that was stored in my password manager, and it was only that old phone number with weeks left to live that got me back in.
Yeah, but my work account is tied to my work email and my personal account is tied to my personal email. Not sure why anyone would want their personal account tied to their work email and vice versa.
Strangely enough the only consistent way I could figure out to get that back end username was to make a post on their official forums which would then show the real username next to your post (after you made a config change in the forum settings). So now for every administrative user I helped to setup I had them posting random stuff that really had nothing to do with anything just so they could figure out what their actual username was.