Apparently some (maybe all) distros that are now requiring an initramfs to provide /usr before init loads expect the initramfs to handle the fsck of /usr. In fact unlike / e2fsck will refuse to fsck a read only mounted /usr
So, essentially, anyone using this initramfs to get /usr pre-mounted can't fsck their /usr without booting from some live environment.
Personally, I would like to see e2fsprogs get modified to allow the fsck of a read only mounted /usr but they appear to have taken down their bug report/feature request link so I am asking here :(