Sure, you could. The design would do something like:

We need a bigger memory controller.

To get more traces to the memory controller We need more pins on the CPU.

Now need a bigger CPU package to accommodate the pins.

Now we need a motherboard with more traces, which requires more layers, which requires a more expensive motherboard.

We need a bigger motherboard to accommodate the 6 or 8 dimm sockets.

The additional traces, longer traces, more layers on the motherboard, and related makes the signalling harder, likely needs ECC or even registered ECC.

We need a more expensive CPU, more expensive motherboard, more power, more cooling, and a larger system. Congratulations you've reinvented threadripper (4 channel), siena (6 channel), Threadripper pro (8 channel), or epyc (12 channel). All larger, more expensive more than 2x the power, and is likely to be in a $5-$15k workstation/server not a $2k framework desktop the size of a liter of milk or so.

Risk cannabalising sales from their other products?

For example Nvidia seek to ban consumer GPU use in datacenters as they to sell datacentre GPUs.

If they made consumer platforms that can take 1tb of ram etc, then people may choose to not buy EYPC.

Afterall many cloud providers already offer Ryzen VPS's.

That's a question for AMD and TCMC. They only have so much space on the silica. More memory channels means less of something else. This is not a "framework platform" issue, it's the specification of that CPU.