... however we know that the elliptical planform does not give us visible benefits ...
Oh, it gives
visible benefits -- it looks better! Just maybe not palpable benefits.
I have a book on designing full-scale aircraft. It's written for pilots, so the math is very much dumbed-down, but it has a section on wing planform and where the stall will start. It points out that the reason you see so many light aviation aircraft with no wing taper isn't just because the wing's easy to build -- it's also because such a wing will stall in the center first.
I've spent a little bit of time with full-scale aircraft, and something you often see on small and medium-sized general aviation planes with tapered wings is a section of angle-aluminum, six to twelve inches long, riveted onto the leading edge of the wing at the root. That is there
specifically to induce stall at the wing root before the tips stall. A determined pilot can still stall a tip, but not before the airplane has stalled at the root and given him lots of warning about what's going on.
If the various experts, you and Howard included, are to be believed, then designing a stunt wing specifically to minimize induced drag (or overall drag, for that matter) means giving up on other facets of performance that may be more important.