Yes..... Bell shot a lot of elephants with the .275 and the .318.
Does this make those cartridges "good" for elephant?
Ask the ghosts - and there are quite a few of them - of those who tried to "do a Bell" and were off-centre by just a tiny amount.
Bell was a superlative shot, by all accounts, and did a lot of his hunting in the open. Not the tick stuff.

Or read Elmer Keith on why he recommended larger calibres for Elk than the '06. Despite its THEORETICAL performance on big game, what he found from EXPERIENCE was that he spent far too much time as a guide, tracking wounded game for clients who had used the calibres being lauded as totally adequate in this thread.

Just because something CAN be done, does not make it a good idea.

Likewise, pretending that a man who can shoot his .338 well off the bench, but not standing, has problems with his "magnum" is simple ego-stroking. Those of us who shoot the bigger calibres know that recoil is MORE of an issue off the bench than it is is freehand. The issue is not one of recoil, but of coordination, skill and practice.if you cannot recognise this, then I have to question your understanding.
I speak as someone who can shoot consecutive sub-MOA groups over a bench with my "magnums", but who lacks the physical coordination to shoot well offhand with a .22RF or any of the small centrefires.

It sucks, but I do what I can with what I have.

Yeah, bullet technology has improved, but Bell was using the old technology. Don't pretend that technology has made us all into Bells. It has given us a little more margin for error. Not orders of magnitude. Nor has it rescinded the laws of physics.

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Back to reality.
I would argue that the "perfect" hunting cartridge is a myth. It would shoot flatter than a .220 Swift, have the recoil of a .22RF and the knockdown power of a .505 Gibbs.
In practice, every choice is a compromise. It needs to shoot flat enough to make hitting your target at ranges that are only roughly known and without the time required to play with rangefinders and sight adjustment.
It need to throw a sufficiently heavy projectile to reliably put a hole in the vitals even when the angle is sub-optimal.
....... AAAAND you need to be able to shoot it well. That - within reason - is more an issue of practice, familiarity and knowing your limits (I mentioned my own, above).

There is a lot to like about medium-bores like the .375, and a lot of hard experience behind the old saying that you should shoot the largest calibre that you can shoot well. For big game, at any rate.