That is the truly epic thing about his, uh, epics. He basically used his own evolution of thoughts as a parallel for the history of a culture -- all by a single person. The languages themselves evolved in his head, and he documented all of the versions as if they belonged to thousands of years of linguistic divergence.
Star Wars and Marvel still evoke debates about canonicity, but at least that's a bunch of authors taking things in their own directions. Tolkien achieved that kind of argument about canon all by himself.
It's actually ripe for fanfic, and why people really shouldn't get so up in arms about whether modern expansions of Middle-earth are in conflict with "canon". He explicitly called for "other hands and minds" to expand on his work. But what he achieved all by himself is so masterful that it's understandable that some want to think of it as a pristine canon unto itself.
Star Wars and Marvel still evoke debates about canonicity, but at least that's a bunch of authors taking things in their own directions. Tolkien achieved that kind of argument about canon all by himself.
It's actually ripe for fanfic, and why people really shouldn't get so up in arms about whether modern expansions of Middle-earth are in conflict with "canon". He explicitly called for "other hands and minds" to expand on his work. But what he achieved all by himself is so masterful that it's understandable that some want to think of it as a pristine canon unto itself.