the real question is:
IS blitz ACTUALLY bad?
Not inherently. Nor is it good. It just is. It is fun. It can develop pattern recognition. It can help you develop some techniques through practice. It can cultivate sloppy and shallow thinking, as well as other bad habits. It can reinforce cheap tricks that don’t work when the opponent has time to think.
true 
Blitz is bad because you don’t get enough time to think, and often loses to the clock in a winning position.
This is exactly why blitz is good
Blitz is bad because you don’t get enough time to think, and often loses to the clock in a winning position.
This is exactly why blitz is good
*Most of the time...
I think faster time controls depend more on instant pattern recognition & intuitive moves while slower time controls depend more on deeper thinking about move combinations. So they develop different aspects of a chess player's skillset.
Although I'm bad at both aspects & just play for fun, this is what I perceive. You need both the ability to think deeply as well as move quickly and intuitively. So rapid/blitz serve different aspects.
Good
the real question is:
IS blitz ACTUALLY bad?
Not inherently. Nor is it good. It just is. It is fun. It can develop pattern recognition. It can help you develop some techniques through practice. It can cultivate sloppy and shallow thinking, as well as other bad habits. It can reinforce cheap tricks that don’t work when the opponent has time to think.