The bike industry needs more cassette cogs, roughly one additional cog every 7 years. Despite us being past diminishing returns at 9 cogs, it does create sales buzz among gullible early adopters, and the dream demographic for the industry: trend followers with high discretionary incomes.
But the most important aspect of the N+1 cog thing is that it allows the industry to render "useless and obsolete" previous generations of equipment, and allow shops to be able to say straight up to customers: "9-speed is like 20 years old; we cannot get parts for this anymore". So if you cannot source a 9-speed chainring, then a new bike is recommended.
When we got to 11-speeds, even the most gullible new bike buyer was skeptical about the need for a proliferation of very thin cogs in the rear. And having to pay $150 for a cassette and $50 for a chain. So the industry had hit a wall with respect to the N+1 strategy. The workaround for the industry was 1X systems, i.e., eliminating all but one chainring. Eliminating 11 useful gear ratios now provided the impetus for further proliferation of cogs, as a makeup. So unimpeded, we can further march on to 12, 13, 14 etc. speed drivetrains.
And as we all know, using a front shifter is SO HARD.
Adding more cogs in the rear will necessitate new frame standards, such as widening the stays on road bikes beyond 130mm to 135, 142mm and beyond. This will have the future benefit of truly rendering previous generations of frames: "useless and obsolete".