Sadly your research is spot on, BMW and many other leading Marques give bean counter led advice not engineer led advice. All the major manufacturers over the last 20 years have incidents of catastrophic failures. I believe it began with dropping duplex timing chains and moving to simplex alongside moving to plastics for internal chain guides added to the insistence that long life oils were fool proof. Add that to the genius who thought it was a good idea to put timing chains at the back of engines or in the middle making them completely inaccessible without removing and completely striping the engine! main dealer labour costs meaning the unit is often scrapped. BMW Mercedes Audi VW Jaguar Toyota Nissan Citroen all guilty
The "Life" of the vehicle became the end of the Manufacturer Warranty so in most cases 3 years or 60k after that they could effectively wash their hands of any problems as most cars were now outside their dealer network for service and maintenance so they could look down their nose and blame poor service or materials..
My own X5 fully serviced by BMW and a local BMW Specialist suffered chain guide failure bits of which clogged the oil pump you know the result!! but due to my X5's age and mileage BMW were not interested fortunately I had a 3rd party Warranty. The plastic chain guides have a life of 80 to 100k ? due to heat cycle hardening and accelerated wear due to oil degradation. My X5 comes with a ZF Auto box sealed for life say BMW service every 80 to 100k kilometers say ZF. BMW are not alone look at VW Audi tales of woe or Mercedes or Toyota or Nissan the list goes on.
After a complete engine rebuild on my X5 and having the opportunity to examine the internal parts I realized that the main chain tensioner is a cheap spring assisted hydraulic device, the spring over time becomes annealed with the heat cycles that the engine goes through, the same heat cycles that are hardening the plastic guides. At engine start as the spring is soft and not applying tension there is a small moment between oil pressure building where chain slap can happen. Result is chain guide accelerated wear leading to failure being simplex chains they also stretch. At reassembly I have fitted a pre-oiler to give full oil pressure at ignition on to help avoid many of the issues I combine this with 6 monthly oil changes, my gearbox is serviced by a ZF agent according to ZF requirements and all suspension bushes (including the swing arm bushes which BMW advise cant be changed) have been replaced and where possible switched to Poly Bushes. My "improved" X5 is a great car 16 years old pulls the horse trailer like it isn't there copes with mild off road use and is used properly every day. There will always be jobs to do but for now I am comfortable with the X. Could BMW have avoided many of the issues, in my opinion yes. A few extra £ spent at manufacture a few extra service intervals small costs to the manufacturer would re-enforce the myth of great engineering.
When we buy a car we are a bit like the Tom Hanks character in the film Apollo 13. just before launch he says something like "here we are sat on top of billions of dollars worth of components all supplied by the lowest bidder" THE BEAN COUNTERS STRIKE.
If we understand the short comings under neath there are some really good cars we just have to dig a little, hopefully not in our wallets.