Parsers aren't the problem. It's using a parser to belittle someone else that is a problem.

1) SE cannot tell you are running a Parser. They cannot see what is running on your PC.
2) Running the parser for personal use, and thus not communicating its data to anyone in game, is violating nothing.
3) Using said data to belittle, harass, or "expose" someone's bad play IS the violation. At that point, because of the outburst, SE will know you are running the parser. Even so, the reason you will most likely receive a ban in this case is for HARASSMENT, not for running the parser.

Honestly, this logic is not that hard to understand.

TLDR: Don't use numbers in game to belittle someone else. Don't be mean to other players. Is it hard to be a quality human being?