I noticed "systems without sufficient boot randomness" and would like to add to this.
With the changes to /dev/random going from 4.16.3 to 4.16.4, my low-spec Chromebook does not reach the login screen upon boot (it stays stuck on a black screen) until I provide a source of entropy to the system via interrupts (e.g., holding down a key on the keyboard for 5 sec or moving my finger across the touchpad a lot). After providing a source of entropy for long enough, "random: crng init done" prints out in dmesg and the login screen finally pops up. Detailed information on my system can be found on this bug report I recently worked on: https://bugzilla.kernel.org/show_bug.cgi?id=199463
