While I can not answer for SSG, there are only two executables that I know of that benefit from the compatibility option. The launcher, lotrolauncher.exe, and the client, lotroclient64.exe. I did some digging into this previously. The client used to identify itself to Windows as a Windows 7 program. That might be why the compatibility option seems to work. What kernel changes came with Windows 10 and subsequently Windows 11 I've not researched; but the switch is one done via Windows. I'm guessing that once they rewrite the launcher, this option may no longer be needed.
"No sadder words of tongue or pen are the words: 'Might have been'." -- John Greenleaf Whittier
"Do or do not. There is no try." -- Yoda
On planet Earth, there is a try.
Indeed, in a world and life full of change, the only constant is human nature (A is A, after all :P).
We old vets need to keep in mind those who come after us.