A tube fed lever gun depends on a fair sized cartridge rim for proper feeding.
If you recall, lever guns in .45 Colt didn't appear until a few years ago. Back in the 1800s the original .45 Colt cartridge had a smaller rim which wasn't wide enough to reliably feed in lever actions. I forget exactly when it happened, but the .45 Colt was modified with a slightly wider rim that will now work in lever actions.
My guess is that this new 9mm abomination uses detachable magazines simply because that's the only way it can reliably feed.
I'll have to disagree with you on .45 Colt and lever actions. Right idea, wrong reasons.
In the black powder cartridge era, cartridges employed a long tapered case body, and in the case of shorter lever action rounds also incorporated a mild bottle neck.
The long tapered case ensured that as soon as the case moved aft during extraction, the entire case body moved out of contact with the chamber wall, which was usually power fouled.
The mild bottle neck helped the comparatively low pressure black powder loads seal the case against the chamber wall to minimize powder fouling in the chamber and gas and fouling getting back into the action.
Take a look at the .44-40, 38-40, 32-20, and 25-20 and you'll see all of those cartridges have body taper, a bottle neck, and a heavy rim. All of those are to better manage heavy black powder fouling.
In contrast the .45 Colt was designed to be the magnum pistol round of its era, using straight parallel case walls for maximum powder capacity. It was designed for the Colt Single Action Army, which used a rod ejector and thus there was no need to use the rim for anything other than head spacing of the cartridge.
Colt made the rim as small as possible to keep the cylinder diameter as small as possible.
The parallel case walls, the lack of a bottle neck, and the small rim all made it totally unsuited for use in a lever action carbine or rifle. If someone wanted a dual purpose cartridge that would work in a pistol as well as a carbine, they didn't get a .45 Colt. If they wanted a rifle or carbine, they could not get one in .45 Colt.
Colt did however hedge it's bets slightly by tapering the .45 Colt chamber .007" from mouth to base so that while the cartridge walls were parallel the chamber walls were not. That made extraction easier. Fast forward almost 150 years, we still have that taper in .45 Colt chambers, which is why case life is poor, especially with tier two 21,000 psi and tier three 32,000 psi loads.
The US Army adopted the Colt SAA and its .45 Colt cartridge in 1873.
However, not long after in 1875, S&W introduced the Model 3. The US Army soon adopted a slightly modified version as the M1875 Schofield revolver as it could be reloaded in half the time as the M1873 Colt as it had a break open action that make ejection much faster and also didn't require require rotating the cy,index past the cylinder gate to reload.
The M1875 Schofield revolver was chambered in .45 Schofield. The .45 Schofield was just a shortened .45 Colt. It was shorter because the S&W Schofield revolver was a break open design that used a star ejector.
Since logistics were more important than the extra power of the .45 Colt, the .45 Schofield had adequate performance, and the .45 Schofield cartridge could be fired in the 1873 Colt, in 1879 the .45 Schofield became the standard round for both pistols.
That's also where the reference to ".45 Long Colt" got its start, differentiating it from the "shorter" .45 Schofield.
The US Army switched to the .38 Long Colt in it's double action, swing out cylinder Colt M1892 revolver. However, that cartridge proved to be less than stellar when it came to stopping Filipino rebels and the Army put the .45 revolvers back into standard use before adopting the Colt New Service revolver as the M1909 revolver.
Since the M1909 revolver used a star ejector, Colt provided room for a larger rim and the M1909 .45 round had a larger .540" rim diameter. It was however otherwise identical to the .45 Colt in case dimensions and was loaded with smokeless powder.
The am1909 was an interim solution and the M1911 in .45 ACP was adopted in 1911. The M1917 revolvers were adopted in 1917 to address a shortage of 1911 pistols, and the M1917 was a M1909 chambered for .45 ACP and half moon clips.
However, with the end of the black powder era (phased out in the early 1900s) and "modern" commercial .45 Colt production, two things happened. Colt made the rim as large as it could (.512") and still get them to fit in the SAA revolvers, and switched from the older ballon head case design to the current head design.
The new cases didn't hold quite as much powder but were stronger, had a slightly larger rim, and had a small groove cut in the case above the rim to allow better purchase for an extractor.
That made the .45 Colt practical for use in lever action rifles and carbines, although I'm not aware of it actually happening for several more decades as neither Winchester or Marlin chambered their rifles or carbines in it until fairly recently.
As far as I know Rossi was the first to offer a standard factory lever action in .45 Colt with its Rossi 92 beginning in the 1960s.