Is this really true? Or just when using Red Hat systems? I don't know too much about the boot chain, but I always thought that after the ROM stage, usually GRUB would take over directly from the UEFI.
If you don't use Secure Boot, UEFI firmware can boot directly to grub.
This will, of course, not be signed by MS, so if you use SecureBoot, you need to handle your own signing. Set up is not automatic AFAIK, but once you've created your keys, signed MS's boot key (if you need dual boot), replaced the UEFI's key with yours and set up your package manager to sign every kernel update, everything works well enough. Haven't had a single issue with this in 4 years of running on "enterprise" HP laptops.
Without secure boot, I don’t think there is any need for the shim, but if it’s still used or not in those cases, I do not know.