Why do websites ask for an email/password when logging in via social networks?

Question

Social media

An example is specifically Toaster or other sites. Why when registering - if I choose "log in via social network" the site still forces me to specify an email and password. Email, for example, I would understand (for example, VK does not send email to oauth), but why the password? it turns out that this is not an entrance through a social network, but an entrance through a social network + registration.

Answer 1

An account is created to which a social network is linked for quick entry. There can be several such social networks per account. Accordingly, you can and the same acc. quickly log in from any available social network.

If you log in only through a social network, then when you log in through another, you will be taken to a completely new account that has nothing to do with the first one. This creates duplicates and confusion for both the developer and the user.

Answer 2

For the subsequent distribution of "useful" letters, according to the administrators of those sites ...

Answer 3

In addition, many sites want to have their own user base, and use social networks for quick registration (with a ready-made avatar, name, etc.), and the word "login" is like a lure.