Thanks for bring this up, Moomba! ^
This is a tough one. I'm in general inclined to avoid rules and regulations that would discourage people from posting their TRs. While I agree with those who point out that there's something annoying about having to click through to another site, the alternative is, what, for that person not to share their TR at all? It seems to me that it should be allowed.
However...
I draw a distinction between people who host TRs on their own blogs/sites for the sake of convenience and those who effectively post links to their TRs as a means of drawing traffic to their commercial blogs or sites. If someone is making money from ads on their site, then I don't care for them using FT in general or the TR forum in patrticular to boost their take.
And one other thing: For me, the main reason I dislike TRs hosted outside of FT is that it makes it difficult to discuss using normal FT tools. You can't easily link-quote specific parts, and it's certainly not there for easy reference for others to see. And what happens if, for whatever reason, that person closes down their site? Then the TR is gone forever.
So I guess I don't like it, but I'm not sure I would take the step of banning it.