I find the same. Combine that with sleep being far more frequent that restart, and boot times are unimportant.

I think the need for faster boot comes from people who scale cloud servers or containers up and down a lot.

Yes. But a cloud VM instance can boot very quickly, because it has fixed hardware and does not have to probe for physical devices. Waiting for enough random events to happen to init the encryption used to be a major drain of startup time; likely not a problem any more.

Unlocking encrypted disk isn't I/O bound though.

The key derivation step is designed to take a set amount of CPU time (say, a second), so it's difficult to brute force.

Indeed, it ought to take time to afford protection. Optimizing the rest may be fun, but already changes little in a laptop.

(A cloud instance with a disk without encryption is a different business.)