I have heard the Fender vs CBS story many times. It has become the stuff of legends.
Yet, I have yet to see a single piece of statistical evidence that preCBS guitars are any better.
There is quite a bit of anecdotal evidence that Fender fell off the face of the Earth after being acquired. Yet, there is no verified evidence whatsoever.
When CBS bought Fender, they didn't fire everyone. Most of the pre and a post acquisition employees were the same. Did they forget how to do their job? Did they forget the process?
Probably not.
If post acquisition guitars are lower in quality, there has to be some sort of explanation.
Does anyone have any verifiable data?
I'm not a Fender historian - but as you say, the legend is what it is, and the market reflects it. That said, some of the best Fenders I ever played were built prior to the CBS buyout. While things didn't change over night, they did change as bean counters exerted more influence over production and there were design and material changes. And no doubt there was turnover on the production facilities.
I do know that I played a lot of 70's Fenders that weren't very good instruments. And I have played some that were great. My personal "hit rate" is higher with pre-CBS and also with anything post '08. The late 70's/early 80's are probably considered to lowest point of Fender, but production instruments in those days tended to be variable.
The reality is that due to CNC and other advances, production instruments made today are arguably better on all counts (certainly more consistent) that ever. But the imagined "good old days" will always command our memories and our money.