Advertising is more powerful with uninformed people, mostly casual photographers. Professional photographers look for technical information, reviews, comparatives... and before they buy expensive equipment they do some qualified research...
I applaud your theory; having stated in this busines in ´60 I would love to agree with you. However, it is my experience that those days of certainty (assumed) have long vanished. At least when I was starting out there was the chance of working with somebody who knew more about it than I did; later, that seems to have been changed to a situation where people leave photo-school, college or whatever other hall of learning with about as much real knowledge of the nuts and bolts of the thing as the local postman has. Possibly even less.
Nobody has a studio, nobody owns anything and everything is rented as and when. Great. Just what´s required to create confidence in a set of tools! Considering that I never borrowed nor ever lent equipment, it´s not surprising to me that there are problems for those that do.
Worse, it used to be about mechanical cameras, manual lenses and well-built Dursts. Today´s scene encompasses so much other peripheral paraphernalia that, should something go awry, it becomes very difficult to apportion blame to any distinct part of the messy equation. Is it the lens, is it the sensor, is it the camera, the software? No, frankly, I think it is a culmination of problems caused by the relentless pursuit for answers to questions that nobody was asking.
Believe me, in all my pre-digital lfe I never heard of a fellow pro who had to return a professional-quality lens for replacement because the new one he´d just bought was crap. Today, it seems almost de rigueur. For myself, the worst that happened was a new Nikkor 300mm that had a focussing ring that felt a bit too slack.
And you know what? Photographs today are not one whit better than they were fifty years ago. Different yes, better no.
And then there is the magic of a name as in Leica. All I know first-hand of the marque is that my last employment was with a guy who did BBC TV stills in Glasgow. He had an extensive array of stuff and for set continuity pics he used an M3 with a 21mm because it was the best wide-angle he had, better than anything for his F3. I sometimes printed from the negs and they did have a different look to them compared with Nikon - tonality looked more MF, somehow. Yet, I know another guy who has had several M and R Leicas and has not a lot of praise for either. So, yes, who do you ask for that great advice?
Other than that, the sun´s shining and lunch is being digested.
Rob C