[usr1106]

For root partition sure. But for boot? Normally when you choose an encrypted root partition you get an extra boot partition without encryption. Unless that has changed rather recently.

[brnt]

Depends on the distro. openSuse encrypts all, and has (or had?) slow boot as consequence. I think Tumbleweed just switched away from Grub.

The theory is that messing with boot can compromise your system and leave you vupnarable despite encryption.

[k8svet]

I mean, something still accepts your password that's unencrypted. The solution for this is, yay I get to say it, Secureboot.