I'm in the non Magnum camp too but If I had to limit my centerfire collection down to only one caliber it would be 300win mag. It's the most versatile caliber chambering according to my most current train of thought. It'll do 98% of average person's big game needs anywhere worldwide all terrains possible from close to long range without a fuss. Limiting one's self to only Canadian hunting conditions, a 300 mag is less ubiquitous but still if hunting a moose from across a lake, or a mountain goat from across a mountain, or a pronghorn from across a valley or when trailing a grizzly through a timber, the 300 mag is ready for exceptional situations that a standard cartridge like the .308w (which I love) just can't claim to be as ready for.
Precisely... I am not a proponent, necessarily, of either category of "magnum" or "non-magnum" cartridges... the argument is non-sensical without establishing specific parameters. However, to my mind there are really only two foundational considerations for such a discussion, either the issue is recoil or it is meat damage and I suspect the former is the real impetus for these types of threads.
If this is the case, having the word "magnum" in the name does NOT truly quantify it's status. If recoil is truly the issue, and of course, "meat damage" can be considered "loosely" proportionate (ie. The damage from both ends of the rifle), then there is an X-Y scale that can be applied to the subject. With "X" representing the cartridge possessing (the potential for) the least recoil, through "Y" representing the cartridge possessing (the potential for) the most recoil.
Once the cartridges are aligned on this spectrum, a meaningful debate can be held as to where the "average" shooter's cut-off for comfortable or tolerable recoil falls on this scale... if that point can be determined (all-be-it, loosely), then the cartridges on the "X" side can be considered "Standard," and the cartridges on the "Y" side can be considered "Magnum..." and this because, the underlying impetus for discussion is concerning recoil and not the word "magnum."
There are a host of factors that make the discussion a darker shade of grey rather than black and white. The weight of the projectile, the density of the load, the type of propellant utilized, and the weight of the rifle. Another factor that most shooter's can attest to in the real world is the "type" of recoil. We constantly hear shooter's describing recoil as a "push" rather than "snap," or vice versa... we understand that not all recoil of a given energy is perceived in the same way. There are many factors that can influence this perception, the recoil absorption of the recoil pad (hence the name), the surface area of the recoil pad, the burn rate of the powder, the COG of the rifle influencing the direction of the recoil ie. straight back, or with muzzle lift... etc... etc... kind of like the difference of being hit by a pillow versus a pool cue, when both possess the same energy.
Long story, short... an argument can be made for either; "enough is enough" or "more is better." In some circumstances "enough" will not be enough (a lost animal), and in other circumstances "more" will be too much (meat damage)... I have experienced both scenarios, neither feels great in the moment, but I philosophically fall in the "more" camp as I truly detest seeing (feeling) wounding loss.
Having said that, there is of course a mitigating factor for both camps... and this behooves "all" categories of hunters (not shooters), and that is "self restraint." Regardless of what you choose as your tool (including archery gear), you should be well practiced, and demonstrate the self-control to stay within the limits of your ability and the ability of your chosen equipment... this relates to more than simply the distance to the game animal, but also the animals body posture, your physical, mental and emotional state at the moment of the shot, ie. Are you rattled (buck fever), have you just run 300 meters to get into position and are out-of-breath, is your stance awkward and unstable etc... also the emotional state of the animal... archers can tell you the likelihood of a deer "jumping the string" based on whether it is calmly feeding or standing at high alert because it just caught a wiff of human scent... this also applies to rifle hunters shooting at long range.
It comes down to personal choices, in the equipment you employ and the decisions you make in utilizing it.