I'll put my 2 cents in after scanning through all the posts..
Start off, I'm no expert.. But though out my years of reading and trying out different tires, I do have some sense of it all.
My opinion about general thoughts on tires... Size, compound, suspension set up, wheels, etc makes your car handle totally different.. At the end, I believe in what your thoughts on how the car handles.. In order to achieve this, you really need to try out different set up (Hence at one point, I had 14 SSR comps with different size tires and different width wheels... and sometimes different compound tires).
My definition of "stretching" is going beyond the recommended wheel width by tire companies. Of course their recommendation is generalized so, I would say way beyond what they recommend is what I call "stretching".
Example...
255/35/18 that I run on 10 inch wide wheel could be considered by some as stretched.. but I don't as its the max rim width by tire companies. But to run 235/35/18s on 10, I say that's stretched.
But I do have to admit, Its more for looks than ideal set up for track nor for street driving. I'm sure you all know, stretched look require higher tire pressure and is more likely to loose bead if tires impact. The later part is not fiction but fact! If you stretch the tires so much and you accidentally hit something hard, there is much higher chance for the tires to loose bead. For me, that's not worth risking your life for gaining some special look.
That being said, If you understand all this and want to do what you want to do, than I have no issue with it. But stretching the tires and not knowing the negative affects and then recommending to newbs or others, I think that's wrong.
Another negative effects of stretching I see is looking contact area of tires. For front, some prefer because it rounds the tires and some say they prefer running smaller tires for width of the rim. But running stretched on back, I think it might be good for drifters but not sure about track guys or drag guys
Anyhow, most what I said, I know all of you know.. so just me rambling on.