"Maybe if I click login it will somehow do federated login?" Nope.
Ok what if I copy the /post/<id> from the URL and paste it in my instance. Nope 404.
Hmm...
Aha! I randomly noticed this text:

You are not logged in. However you can subscribe from another Fediverse account, for example Lemmy or Mastodon. To do this, paste the following into the search field of your instance: !fedimemes@feddit.uk

I did that, but it eventually (takes like 10 seconds) came up with a load of random posts and comments from here.
Maybe... if I click on Fediverse memes@feddit.uk - 792 subscribers?

Success!

Just like typing in someone@yahoo.com. 🙄

[–] gandalf_der_12te@discuss.tchncs.de 3 points 1 day ago* (last edited 1 day ago) (1 children)

"Maybe if I click login it will somehow do federated login?" Nope.

Ok what if I copy the /post/<id> from the URL and paste it in my instance. Nope 404.

Yeah, these two are major pain points. They are unintuitive, i would argue. If you click "login", it should ask you for your username. If your username is lisa@bumblebee.com, it takes you to bumblebee.com and lets you finish the login process there.

The /post/<id> should have been fixed a while ago. I don't know why it wasn't.

[–] zalgotext@sh.itjust.works 1 points 1 day ago (1 children)

I don't think the lack of "federated login" is unintuitive. You wouldn't expect going to gmail.com and logging in with your Yahoo credentials to work, right?

Having a "federated login" service would probably either add a ton of complexity for instance owners, or someone would implement some super naive and insecure centralized solution, leading to a bunch of people's creds getting stolen.

Getting the post/<id> thing to work across instances would be a pain too, because it would require instances to all coordinate post IDs to ensure collisions don't happen, since far as I can tell, the id in the URL isn't globally unique.

[–] gandalf_der_12te@discuss.tchncs.de 1 points 11 hours ago (1 children)

The motivation for federated logins would be that often you're linked to a post on another instance, such as https://someinstance.net/post/12345 now when i click on that, in the web browser it opens on the other instance, and now what if i want to comment?

[–] scott@loves.tech 1 points 3 hours ago

Federated logins make sense for forums and websites where you have access to content such as PeerTube.

For forums, logging into the forum with your fediverse account would actually be ideal since you can use a forum-style interface to navigate the topics, which would be easier than trying to navigate the same topics on Mastodon. Same thing with PeerTube. You may want to watch videos on PeerTube and comment right on their website without creating a PeerTube account. With federated single sign on, you can post with your existing fediverse account.

We have that on Hubzilla and it is called OpenWebAuth. We can log into other instances and comment directly on their instance as ourselves after logging in.

[–] Cardboardboxo@sopuli.xyz 2 points 2 days ago

Well most apps take care of that for you. I'm on a different instance and all I had to do was hit the reply button. For most people setting up the account and choosing server is the hardest part. If I handed someone my phone with an account already made they wouldn't even know they are viewing and commenting on different servers hosted by different people. They would just think its a different looking reddit clone. But I don't agree that logging in if your not on your home instance is hard as it requires you to find the post again. Some apps have an option to pull up the post on a different instance but last I checked that's on an option on the web browser.