I would dread going back to a car without a CANBUS. Cars are WAY more easier to diagnose now.
Boat engines have CANBUS too. I had a bad miss on my 2017 Cobalt. I kinda shotgunned the repair by replacing the 4 coils. Later bought my Rinda scanner. If I had bought the Rinda scanner first, I would have know exactly which coil I needed to replace.
I am fairly recently retired. I also worked for GM for awhile. The tech makes working on your vehicles easier...not harder. My last job was a designer for test equipment for high speed internet protocol testing. We were designing test equipment for vehicles because eventually, all sensor will be on a high speed data bus to reduce the miles of wire in a car. Saves weight and makes design simpler.
My Rivian is the most complex vehicle I have ever owned. It has only 7 modules in it.
I think you have to keep in mind, you have the understanding to troubleshoot and repair these data network systems. The average mechanic of today, does not appear to have that level of knowledge and skill. Just watching both South Main Auto and Pine Hollow Diagnostics on you tube, these guys fix those kinds of problems all the time. I would love to have their level of skill and knowledge and understanding but it takes a lot of time, patience and equipment (scanners) to get there. Yes I have an Autel MS 808 scanner, it has helped me fix a few things, but I feel like I need to go back to school for this stuff, lol. Which, I certainly wouldn't mind doing!
I prefer my old school process of elimination troubleshooting, like the fuel starvation issue I diagnosed on my old boat, with the separate outboard fuel tank test:
boat ran fine on the outboard tank, WOT RPM was now 4800 like it should be, vs 3800-4000 as it was.....
conclusion:
anti siphon valve and/or fuel pick up tube
no scanner would tell me that, lol!
2 things I have learned troubleshooting marine engines....
hard starting/rough running, always check for water in the cyls first....
fuel starvation....hook up the outboard tank first, to rule out the boat's fuel system....
the rest, is similar to old school vehicles we grew up with (well if you're of a certain age)......