your post is valid, but it also comes down to personal preference.
with the exception of back (only he and yates), i would not rate ronnie top of any list for bodyparts.
i'll give a few examples. again personal preference, but most will agree with me, that ronnie is not the person when you think of:
thighs: platz, demayo, warren, dillet, munzer
chest: arnold, haney, ruhl, louie, bertil (ronnie's gyno)
delts: ruhl, levrone, dillet, nasser - all have bigger and rounder delts than ronnie, although his may have been more seperated. but it seems most will agree that bigger, rounder delts are more impressive.
biceps: arnold, priest, bertil, beckles, boyer coe, if anything, coleman is more at the top at this list than the others.
again, ronnie would on the list of 'best ever', but would not be the #1 guy people look at.
I'll break down your "argument" part by part.
Thighs: All of those guys have good thighs no doubt, but all of them were at least missing 1 thing, whether it be size, seperation, definition or quad sweep. Ronnie had "all" of these things and more. Imagine a near 300 pound Ronnie with these attributes standing next to these guys, lol. Ronnie would put all of them to shame.
Chest: I'm sorry, but no one can come close to Arnold's and Ronnie's chest, no one. Arnold and Ronnie has great thickness for up & lower chest, seperation and striations. To top it off Ronnie's and Arnold's chest looked harder than those guys.
Delts: Again you are mixing up with having "bigger" delts than having "better" delts. All of the guys you mentioned have big delts, but are lacking the seperation and definition than Ronnie has. Ronnie has the seperation, definition, round delts and they are huge. It doesn't get any better than that.
Biceps: All of the guys you mentioned including Arnold have great biceps, but are lacking the definition, dryness and split that Ronnie has. Plus Ronnie's biceps dwarfs priest, bertil, beckles, boyer coe. No Contest.