Indeed. But there was an adaptation before Peter Jackson's, namely Ralph Bakshi's 'The Lord of the Rings' from 1978. While I'm fairly certain the later movies didn't try to recreate the earlier one, they still would at least count as a reboot.
I don't think it counts as a reboot if they're both based on the same source material.
If Tolkien had decided to rewrite the books from scratch, that would be a reboot.
If Tolkien had decided to rewrite the books from scratch, that would be a reboot.