I believe that RTL character is one of the main failures of UNICODE. This should be part of the markup / rich text, not part of the plain text.

Even without the RTL directive, they might have used something like sourcе.html — which contains a non-ASCII glyph. So while RTL is problematic, I'm not prepared to call it a failure in that generally problematic space of unifying human communication.

I use it when I write Hebrew mixed with English...