This has some advantages but there are negatives too. Do I really want Google or Facebook to get a notification every single time I log in to a service because they get an email with a "magic link"?

Google / Facebook already know enough about services used, do we really want to transfer even more information their way?

Also, another trouble with this is the loss of anonymity.

There are very few places to register an email address without an SMS number. There are few places to get an SMS without a real name and address.

Yes, I'm sure there are places to get these things for someone willing to put in a lot of effort, but for everyone else, their email provider has their SMS, their SMS provider has their name and address.

So by requiring email as authentication, essentially every online identity comes back to your real name and address through a small number of hops.

It used to be possible to spin up a TOR session and interact with real services you would otherwise use. Between the crunch on anonymous email and cloudflare's endless captchas, TOR is increasingly useless for interacting with normal services.

This is a feature, not a bug. Unfortunately it turns out that many people are abusive when anonymous and use that to their advantage so anonymity has been curbed to keep control over that problem.