There's a reason why enterprises don't give you an admin account on Windows. Sure damage can still be done, but the blast radius is highly reduced. It was like the first rule I learned about Linux back in the day: don't ever log in as root, don't even bother enabling it. Hell it's not even a good idea to do it on an offline computer cuz you might accidentally bork something yourself. The barrier of at least a password to install system level software or delete critical files is a good one to have.

It only limits the blast radius on multiusers systems or when people do not follow basic security measures like having a different password on each computer. I agree it is a good one to avoid breaking the system yourself too easily but that is only if you don't blindly copy paste commands with sudo.

The only thing it mitigates really is how easy a malware can hide in the system once already present. But as said earlier once running under your username it is game over, your data is right here ready to be stolen, compromised, altered, destroyed or encrypted.