Well, I concur; back in the days, I have created quite a few websites with business logic in RXML.
I'd think that both RXML and its Javascript based successor Remixml are both Turing complete and can be used as generic programming languages (within reason). Which is not to say that creating complicated applications in those languages is a good idea.
I hate the ambiguity that semicolon-less Javascript creates (a newline in the wrong spot, and your code starts to misbehave).