I've never gotten that dialog, and have not had any issues with the accounts I've added. Since they're my work accounts, 99% of them share my work email as account name.
So does that mean I've just been lucky, in that the sites I've signed with have provided a sufficiently unique label? I feel I didn't fully get what the issue is.
The whole online identification is seriously unreliable and full of big wholes, and much bigger risks, yet we build our whole life on top of it. Still using passwords after decades (Yes. Decades!) of serious harm caused by insecurities with it, and trying to patch with plasters or just some paint?! We are so damn stupid, almost no week goes by without some online system gives away serious bits or complete set of personal details of the masses easy to abuse and we just sit in the middle of the burning room like the coffee sipping doggy with that stupid hat and smile in the meme 'this is fine, this is fine'. Lets choose some longer than 8 character password, different for all system just to be safe, we are going to be fine, we are going to be fine.
Even though it might be a dumb feature as seen from the users POV, it seems sufficiently special that it's something that I would assume one would want to have feature parity on.
I would imagine that, if that is their expectation, they would include the issuer in the label themselves, so, none of its products should have any issue.
The problem comes from using other provides -that use the "issuer" field to store the issuer (how quirky of them, amirite?)- while having the same email as identifier.