Mike:
I think your reasons of wrong products, tools, and damaging the factory paint life`s expectancy is somewhat correct.
I would say the biggest problem is using a polisher or buffing machine incorrectly due to wrong techniques of such machines coupled with wrong pad or product choices for the surface being corrected and perfected.
Someone within this forum made a statement that if a detailer is charging by the hour, that detailer better have the right tools (polishers and enough pads) to complete the job in a little time as possible and not be "inefficient".
That said, the amount of time spent correcting and perfecting a vehicle`s paint can be attributed to three things:
1) How "perfect" does the client want the paint?
2) How much surface area does the vehicle have?
3) As mentioned, the tools available to the detailer and their expertise and abilities in using them CORRECTLY and efficiently.
There is is the law of "diminishing returns", meaning how much time is spent and what return do you get for that time spent can greatly impact the hours spent "perfecting" a vehicles paint. Getting a hammered Chevy Suburban or Ford Expedition to look like it is ready for the Pebble Beach Concours D`elegance is much different than getting a garage queen/rarely driven MGB Midget ready for a local drive-in weekly car show, as an example of items No. 1 & 2.
I will not dis any detailer, professional or hobbyists, who spends those hours perfecting the OEM paint to level that has that insane, head turning appearance of perfection.
What is insane or more correctly "uneducated" (AKA stupid) is doing so without the aid of a Paint Thickness Gauge (PTG) to know the true thickness of an OEM paint and how much the OEM surface is compromised in doing so. That has been the subject of great debate in this forum about removing OEM orange peel and how thin today`s clear coats and paint surfaces are with modern manufacturing techniques/processes on most vehicles. (I have recently learned from Merlin that orange peel is actually "programmed" into robotic painters to cover up "minor" sheet metal stamping ripples and imperfections. Really?!) It is one of the reason you and other professional detailers post pics of PTG readings when doing a detail as proof of that.It is just part of the detailing process to verify the actual paint thickness throughout the vehicle BEFORE you begin so a detailer knows what areas may be problematic and require special attention. That process, to me, is the BIG difference between a professional and an "amateur" detailer.
SO, the answer is "because a client wants absolute perfection and they have found a detailer that can do that". Is it efficient time-wise (and hence money spent) to perfect the paint to the Nth degree? NO, not to you, Mike. Is it the right thing to do to an OEM paint and thin it so much that there is no clear coat & paint for future correction OR the life expectancy of that surface is greatly reduced? NO, not to you.
Then again it is not my vehicle and I am not the detailer who is going to do that.