Probably adds more tension on the couplings and possibly contribute to earlier failure. We used a similar supply line on one of our toilets. It burst one night, failed at the coupling by the tank. Fortunately we were home, heard it and turned the line off. My plumber replaced it with a metal line. He said to never use these, that they had a short life span. YMMV

The "T" can be mounted at the wall stub.