People have been saying this, but IMO it hasn't really been true.
Yes, SIP prevents you from modifying system files. But, you can turn SIP off in five minutes—it just takes one quick trip to recovery mode, and you will never be bothered again. Catalina made things a little bit harder with it's read-only boot partition, but you could work around that with a Terminal command. Place a launchd plist to remount rootfs every boot, and you'd never know anything changed.
"But turning off SIP reduces security!" people always point out. But, look dude, you can't have it both ways! Either you want Apple to prevent you from making changes to system files—in which case, keep SIP, and you won't be able to make changes to system files—or you want to be able to make changes to system files, in which case, turn off SIP! If you know what you're doing, it's not such a huge risk.
Big Sur's authenticated root makes things a little more complicated than in Catalina, but it looks like
the OS can still function without this—I'm hopeful that once Big Sur is officially released and the dust has settled, they'll be a more straightforward way to turn off this nonsense.