No, I recognize that most users probably don't use password managers. But I'm not convinced that disabling pasting helps much.
For one thing, I don't actually think it's that common for someone to copy a mistyped password. Browsers disable copying from password fields, so they would have to type it in a third place and copy it into the fields from there. Most users are not sophisticated enough to do that.
> Also, if you're someone who uses a password manager, does disabling pasting really make you less secure?
It directly encourages people to use less secure passwords. If I try to manually retype a 50 character password myself, I'm very likely to make an error. This isn't theoretical—I've often purposefully lowered the complexity of passwords for sites with these kind of arbitrary restrictions.
It's too bad 1Password doesn't have an auto-type feature.