Honestly who cares about repairability. If you are willing to pay $1,000 or more for a phone and you break the screen then you pay Apple to replace it with genuine parts, or use AppleCare to reduce the cost. Stop whinging that backyard bob does not allow screen replacements at lower cost. In addition this voids the warranty as well if not done by Apple, so there is no real benefit, financially or otherwise to bypass Apple.
Yes Apple charge more however their work is guaranteed and covered, unlike backyard bobs repairs. Why the hell would you want to go "el cheapo" to replace a screen externally to the manufacturer plus parts shipping plus your own time to repair it (further financial loss). Lay off the red cordial. I've never had to replace a screen or battery on any of my iPhone's ever in my life, that's what cases and glass screen protectors are for.
If you want full repairability go make your own phone with your own hardware and this way you are not reliant on the manufacturer and stop buying Apple iPhone's if you don't like the repair options and Apple has no legal requirement to provide parts or service to third party companies and they know this well.