If you can reset your password via email it’s effectively a login mechanism - you’re right. I guess passwords are quicker so it’s another more convenient login mechanism. There are a lot of other “prove you are who you say you are” mechanisms: SMS, rotating auth keys, hardware tokens, biometrics. All with upsides and downsides in security and usability.

Passwords that humans remember are on the low end of both security and usability, so I understand your frustration! Password managers work fine but really they’re duct tape pretending to be something like a hard token.

I’ve seen websites do what you say - always log in with an email verification. It’s not bad. My favorite is a push notification to my phone + watch.