@Umbrecola Sorta.... but Tolkien himself is an icon now and can be considered a powerful source. But it's people borrowing from each other after someone else borrowed from Tolkien. It's like viewing Tolkien as the original source, but instead of taking it directly from him, they are borrowing from other works.
Like some people got ideas from Tolkien, and then people copy that and others copy the copy until everyone is copying each other rather than using the original source.
These isekai are using ideas from Tolkien as a base and the world building from Dragon Quest.... but then instead of using the direct source, they are using other people's interpretation...
They are using other isekai authors instead of the source which is RPGs.
The very idea of the Isekai is from games where you play as a character that was summoned. But I read so many Isekai stories based off this and barely played those games... I don't even remember which games did that.