iOS is more secure than Windows was

When Windows, macOS, and the Unix system, in general, were built, it was at a time when they were a bunch of nerds who didn't think about and want to be bad actors. Every process had access to every other process. So if you were a bad actor you could abuse that fact.

iOS on the other hand is built such that no single app can take over the system or affect other apps. It was built at a time when people were a lot more security-aware.

If you control all the pieces, your level of innovation and control can be significantly higher.