Because the boundary between running it yourself and having others run it would normally be fluid. It makes sense that after you run it yourself, you'd like friends and family also to run it.

Also as said in this thread, limit of 3 concurrent apps, have to reinstall every week, have to own a mac with xcode.

Many devs use TestFlight to distribute links to beta testers and friends a family. It's "free" if you pay the $99 Apple dev. The initial part is not frictionless because you still need to have your approved by Apple, but to the end users it's not any different than downloading from the App Store.