They 100% did not let the power users and DIY scene exist. It only existed by exploiting OS security vulnerabilities. Every new iOS release required finding a new way to crack it. That's why a lot of people chose Android.
Once native APIs were available, that was true, but before it was even clear that the iPhone would have an app store, they very much did let it flourish.
[0]: https://www.macrumors.com/2021/03/03/scott-forstall-pandora-...
[1]: https://mjtsai.com/blog/2026/04/06/apple-creating-all-the-ap...