You're still at the mercy of Apple giving you a valid (and revokable) app development certificate. Apps installed with a development certificate expire after a certain number of days. There's also a limit to the number of devices you can use with a development certificate.
There are enterprise distribution certificates that don't have these restrictions, but using them to distribute apps outside of the company will end up getting it revoked. (Like what happened with Facebook)
> As for the distribution, you can distribute your App open-source and let your users compile and install it themselves.
Because non-technical users will surely do that.
> The reality is this: You cannot mass distribute proprietary App's that Apple has not approved.
I feel this is the only point relevant to this post.
Yes, you can invite your developer friends to try out the app you wrote yourself. But if you actually want to make money from it, you need Apple's approval.
There's an entire ecosystem that surrounds sideloading apps that are not in the app store. They're not all developers or technically inclined people, it's a very easy thing to do and can be done on any OS. Developers can distribute an IPA that isn't valid for your device, and you use an extremely simple GUI tool (Cydia Impactor) to resign, repackage, and install all in a few steps. You don't need to be a technical user to do this. You just sign in with your Apple ID in the app (or any Apple ID, it just needs to be in the program as a free or paid account).
That's how developers install their own apps in development, prior submitting the app to Apple for a review.