I think it really comes down to the fact that the ideal choice in chamberings for a given species is not really about the cartridge at all. Asking “Why talk down magnums?”, isn’t, in my opinion, a fully-formed question.
Why talk down (or up) magnums for WHOM? That’s the fully-formed question, IMO.
As has been already mentioned, the issue of recoil-induced poor shooting is very real. As one of my favorite gun writers, Craig Boddington, very rightly observed, “Recoil sensitivity is like bad breath, it is very difficult to self-diagnose.”
Of course, nobody HERE is recoil sensitive…, but I’ve seen you guys at the gun club! Yes, I’m looking at you, with your scattered groups, good first shots followed by errant second and third shots, and your obviously tense grasp of the rifle.
An then enter the machismo factor. C’mon, who’s going to be the pansy-ass, girlie man that admits, “Ummm, I tried a magnum and it’s just too much for me?” Unfortunately, no matter how poorly people shoot, they tend to blame EVERYTHING except their own recoil sensitivity for the problem and they just keep on missing.
IMO, the cardinal rule is to start your consideration with the minimum gun suitable for the game, and then increase size only to the most gun you can shoot well.
This is very difficult for many to do, however! See also, above comment about the machismo factor. You have to have a lot of both self-awareness and self-confidence to be “that guy/gal” who shows up for an elk hunt with a plain, old, boring, “under-powered” non-magnum while all the other hunters are stroking their shiny new .300 Ultras and .338s, and there’s even that one guy who’s got a .375 H&H and he’s sneering at you and your wimpy rifle from across the campfire.
I talked to one very experienced safari huntress about her choice of rifle and even SHE was almost apologetic about using a .30-06! Why? Well, it’s just not a “safari caliber”, of course. The fact that she collected dozens of species over multiple safaris I would think proves the point that using chambering that you can shoot well is what produces results.
I think the other principle knock against the use of magnums for whitetail is, really, about how much deader do you really need that deer to be?
Magnum devotees will point to the massive damage that a magnum hit produces as evidence of the benefits of a magnum, but there’s a lack of comparative evidence here. Would a plain, old, boring, non-magnum have dropped that same deer just as dead?
Of course, we’ll never know for sure, but that won’t stop people on both sides from answering the question and creating “evidence” that backs up their view.
Grouse