I graduated in physics so I am no stranger to math notation quirks and I think I also do understand their usefulness at times (conciseness in notation, etc). And it can be dangerous, too. As soon as the notation lures you into doing transformations that are invalid.

Doesn't help that then notation is often poorly defined, and sometimes a weird mix of notations is presented.

Overall the situation is also not pleasant for math people changing topics, or physicists reading papers from physical chemistry professors who 'grew up' in mathematical chemistry.