It goes back to primacy (they say)
I learnt at, and then subsequently worked at schools with heavy SOPs, and schools with the simplicity of almost the same checklist for every type.
I think there's benefits to both, but I think that up until PPL, the people that truly benefit from heavy SOPs are the operator. How do they charge? VDO, how does the AC work its service sched? A/S. Do the math. 50 students doing an extra .2 on the ground each flight adds up over a day, month and year. What's worse is that's less time in the air for them, and many of them need it.
After PPL, and if you plan to become a professional pilot, I think solid SOPs really stand out to employers (as long as you can actually fly as well), and help the process and cockpit organisatin required particularly with single pilot multi IFR workloads. Any company will teach you their SOPs, and if you've never integrated them into your flying by that stage, you will struggle even at that point.
The old boumfah and variations work fine for almost every single and multi engine piston.
The basic problem comes back to priorities. New instructors in particular are obsessed with numbers , don't lose height in a stall over getting the technique right, that AoB is 39 dg not 45, etc.. Lookouts are taught as cursory instead if the most important thing.
Power and attitude seems to get lost. And what happens when your looking at an attitude? Your eyes are outside.
I could go on...