It isn't a "has been" it's simply been surpassed in pretty well every respect by more modern cartridges.
It will still do exactl what it was designed for very well but we have many faster and flatter 30's available today that exceed anything it was or is capable of.
Very true. However.......
One can always find faster flatter cartridges EVEN among the oldest cartridges - eg 300 WinMag vs 30-06 vs 308 vs 30-30. That is NOT the issue because that assumes that newer flatter and faster is always better. It simply isn't.
Flatter and Faster usually means more kick. More kick usually means more flinch and more flinch usually means more misses. I would never hand a 300 Win Mag with 220gr bullets to any new hunter let alone my 12yr old Granddaughter.
Despite the "long range" spirit of this forum, hundreds of thousands of us whitetail and hog hunters hunt edges and farmland where a really long shot might be 450 yards and a close shot might be 5 feet.
If you pay attention to what the bullet manufacturers say, you will also find that many bullets have a preferred velocity for given ranges for given game. Driving a light deer bullet at extreme velocity actually reduces penetration and increases frangibility resulting in lost game. Driving a heavy bullet at Iow velocity on light game reduces expansion and can also result in lost game.
Any hunter prowling the swamps bogs and hardwood forests of North America is "usually" (but not always) better off hunting with one of those "old" technology 308s or 260s or 7-08s or 243s than any powder hungry magnum.
And then there is range manners. Nobody I know willingly sets up his fun gun next to Mr Super Magnum anything. But a 308, 7-08, 260, CM, or even a 30-06 is usually welcome.
And let's not forget barrel life!
I AM NOT KNOCKING THE LATEST AND GREATEST BIG MAGS HERE! I am just saying that almost any cartridge you can name has its place, it's game size, it's purpose, and it's pros and cons.
I simply don't buy the "newer bigger faster flatter" is ALWAYS better argument. In my deer camp we don't argue over whose cartridge is newer bigger better faster or flatter. We argue about who is the better hunter and who is the better shot because that's what puts meat in the freezer no matter what cartridge they shoot.