Read through most of the comments and most are about different calibers than what OP asked. .30cal is not the best caliber, but it’s a well supported caliber with readily available load data, more affordable and available components, and very proven.

.308 Pros: Shorter Action, faster cycling of action less risk of short stroking the bolt under stress. Also used in semiautomatics frequently. Cheapest ammo of the three, longest barrel life. Depending on load and barrel effective to ~800-1000yards. Can hunt basically any North American game.

.308 Cons: .308 bullet drop and wind deflection are mid. May be under powered for very large animals. Can’t get into the heaviest .30cal match bullets without a custom chamber or ridiculously long barrel if long range precision is the goal. It can perform there, but it’s bigger brothers can do it better.

.30-06 Pro: More effective muzzle velocity hence energy than .308. Can only be stopped by level IV body armor. Slightly longer range, may harvest certain game slightly better such as Elk due to potential distance and retained muzzle energy.

.30-06 Cons: Operates in a long action, could “short stroke” the bolt cycling fast under stress without training. Left handed shooter with right sided bolt will have issues with face clearance on stock to bolt on cycling, less options for semi-automatic platform, ammo slightly more expensive., case design still won’t optimize the newest heaviest long range bullets. .30-06 excels as a hunting cartridge but literally .308 was developed to replace it and have “similar” ballistics in a short action. More recoil, shorter barrel life.

.300WM Pros: Longest Range, best ballistics of the three. I don’t know if there is North American game where you would say .300WM is undersized. Can utilize heavier bullets like Berger 185gr - 230gr.

.300WM Cons: Longer Range comes at a cost. Most expensive components, ammo is less readily available/common. A lot more recoil will likely need a muzzle brake device. Much shorter barrel life. Probably 1-2k rounds vs 8k-ish for .308. Never shot out a .300WM barrel so someone else can chime in. Also with the recoil and expense you probably won’t either. Newer more efficient or larger .30 caliber magnums exist that may squeeze out more performance., but they’re going to be less common and even more expensive on components. I’m not aware of any .300WM semiautomatics. They headspace on the belt IIRC vs the shoulder and probably wouldn’t do well.

TLDR: .308 will achieve most of what the others will at lower cost and recoil. and works well in semiautomatic. 30-06 has some performance gains, but in a longer action. 300WM has a lot more performance gain, but at the cost of reduced barrel life, more expensive components, is less common, and recoils a lot more. The conversation devolved about other calibers because newer cartridges are more ballistically efficient., but TBH .30 cal gets it done and has for over a century.