There's another reason, sheer stupidity....
Every year some starry eyed new magnum shooter tells me that they missed a "Good'un" last fall with their 30-06/ 308/6.5X55/270 or another fine deer caliber and so they went and got a 300 Mag Loudenboomer or BIGGER. Most just get the thing bore sighted and sally forth ready to miss or worse, wound another critter or six.
They didn't shoot their old rifles much. Now, with more expensive ammo and more kick, they shoot less. It's a vicious spiral downward, until they give it up or actually smarten up.
Range story....
Buddy and I were shooting off a few centerfires at the 100 yard benchrests, making nice little groups right where they should be. A guy who we had seen there a few times came up and asked if we could take a look at his rifle, he was having trouble staying on the paper. We assented, and he produced a semi custom lightweight on a Remington 700 action in 270. After checking the scope mounts and bedding pressure, we asked if one of us could take a few shots with it. He was grateful, and I snuggled in behind the sandbags with his handloads(after looking over his fired brass for pressure signs)and squeezed off what turned into the first round of a tight 3 rd group. He was amazed, and took it well when we said he was just a tad overgunned.That light 270 with its smaller than standard butt was kicking him a bit too hard, and he was building a flinch big time.
We had brought a 7x57 Mauser, a reworked 93, with a good bedding job and decent scope. It weighed about 1 1/2 lbs more than his prize, and he took it and cut an OK group with it after realizing it didn't hurt to shoot it.He also had brought a brand new 700 BDL in 25-06, and we got that zeroed and he shot it OK. This guy was just too recoil sensitive for that little 270. He said he'd trade it off for a standard weight one and left happy.
Instead of a big caliber Mag, or even a smaller one, most folks would be better off learning the ins and outs of their standard caliber rifles and working on their hunting skills to get within reasonable range. For most big game and bolt action centerfires, that would work out to about 200 yards.
And it would only take a few boxes of ammo and a few range trips to make most hunters deadly on game at those ranges.
There's way more 300-500 yd rifles than 300-500 yd shooters.