It's really not that bad. There are extensions but I decided that auditing their code was harder than just using one of the terminals I already have open.
Autocompletion is a security nightmare, and 2FA really doesn't help, you're blindly trusting LastPass.
I can't imagine not having the app or browser extensions to autocomplete these passwords for me. I even use their 2FA service.
How much work does it take you to create a password for a new account, or retrieve a password when logging to an existing account?