Given that iOS/iPadOS are derived from the same core OS that MacOS is, it had all the same multitasking capabilities and a decision was made to disable them, and then eventually to start opening them up in limited ways (VOIP, for example).
There are typically two complaints about iPad multitasking-- one is the lack of true concurrent background tasks, but the other is the fact that once you switch through enough applications (Safari being particularly galling), that an application basically needs to relaunch because it was flushed from memory. This second concern is mitigated by more memory. Would they change iPadOS to accommodate the extra memory? I'd find it completely bizarre if they shipped a 16GB SoC and flat out denied access to 10 or 12GB of that.
As far as concurrent background tasks though, I don't think the RAM/SSD has any real bearing. The resource you're referring to as the "commons" is battery more than memory.
The point I'm replying to, which you endorsed, was implying that without running MacOS you'd only be able to run "iPhone apps" and there was no reason to add extra memory. My point is simply that you don't need MacOS to benefit from the added RAM and SSD, they can continue to expand the capability of iPadOS.