The rotation isn't actually a required part. Anyone trying to tell you otherwise is, quite frankly, probably a gaslighting Nazi. You'll find it on various military vehicles in the 90-degree orientation quite a lot. Propaganda use typically has the tilt but, again, not having the tilt doesn't mean it's not Nazi shit.

The symbol was also used well beyond India. They actually co-opted the symbol after its popularity in Europe grew from the discovery of Troy:

https://www.smithsonianmag.com/history/how-the-swastika-an-ancient-symbol-of-good-fortune-used-around-the-world-became-the-nazi-logo-180962812/

There are other reasons of course, but I just think that's kind of neat.