email isn't really a decentralized system at all. Google, Microsoft and Amazon own e-mail delivery. Perhaps Google ads customers complained that they could not correlated private @icloud addresses, and we are now witnessing the consequences. What Apple got in exchange from Google, I don't know, I'm sure it is related to their Siri deal.

[citation badly needed]

Come on. Most likely this is just a result of some manager pushing for "improvement": "Why we have two different privacy email alias systems? Lets make unified one, save on maintenace and I get promotion".

And might be there just no one remain as owner of feature to explain them why its bad idea.