Yes. The /dev/random device would formerly refuse to continue giving data even when it had plenty of entropy backing it. The reality is, unless you are in early boot (now fixed by Torvald's RNG seeder) you have enough entropy to generate nearly unlimited quantities of pseudorandom numbers without revealing much of the PRNG's internal state. You only need 256 bits of initial seed entropy to be virtually unpredictable, as long as those 256 bits are strong.

See: Myths about /dev/urandom https://www.2uo.de/myths-about-urandom/

Jiggling the mouse may have made feel better about the security of the software they're using, but really should have been considered a bug (and the UI, a horrible workaround) this whole time.

Now that /dev/random no longer exists, and the kernel now has Torvalds' cache timings based seeder, any software that mistakenly uses it will generate a key instantly regardless of how much mouse jiggling you do.

I imagine the people most burned by that design run / remote into servers.

Yes because it already collected plenty of data from the mouse since boot.