I find the phase "Teslas are a dream to drive, a nightmare to own" is a very good summary with which I lead if anyone asks me about Tesla cars.
I'm more partial to the simple rationale that they simply couldn't scale the required service because service was the reason they were losing money. If you scale production of a product which is costing you more per car in service than your profit margin, you start losing more money (especially if the new, high volume car has even less profit margin built into the price). Lookup how much money Tesla kept on losing when only selling Models S and X. Then consider that Models 3 and Y don't have the same profit margin built in them, so sustaining the same level of service as Model S and X enjoyed before Model 3 flood is simply impossible. Who knew servicing perpetual-Beta cars would be so expensive, eh? Well, Elon knew, but just like he believed FSD would self drive coast to coast by end of 2017, and a million Tesla robo-taxis would be on the roads by end of 2020, he also believed that Model 3 and Model Y would be million mile service free cars by the time he made any significant number of them. Failure to achieve that goal resulted in the parts and service clusterfuck that we have today - they were never ever supposed to be needed, hence nobody bothered to plan to provide them. Notice that even though service didn't scale, Tesla is still not making actual profit on the cars - the thing which took them into the black is selling carbon credits. Once the incumbents have their own carbon credits, or in the case of large manufactures like the VW Group, credit to sell, Tesla may slip back into the red, more loses for every car sold.
Dealer model is not ideal, but after being a direct sales customer of Tesla, I will say it works much better. At the very least there is competition in service. Also, traditional auto-makers do plan for supporting their cars, making sure supply chains have parts, etc. When one of our Model S was in an accident. we had to wait 2 or 3 weeks to even get the a repair estimate. I heard from people at that shop that a month later the wait grew to 8 or 9 weeks. In the dealer model, such demands spawns shops which want to fix the cars, in Tesla model, the expansion is limited to the budget of a company desperate to show profit.