Tensioners seem to be used since 1970's. It is really not the point who used it for an ebike first. (And most likely Gates also offered tensioners for their belts too). Maybe you can give us some information on what was the challenge and how rm solved it.
Come on, although Apple is a company which "adopts" other technologies to their products, RM compared to Apple is at best a mom and pop local computer shop from 2000's, which picks off the shelf components (mboard, graphics card, memory , hdd, power supply etc) and put them in their case.
I think R&M deserves design kudos for their original bike, the Birdy (non-e, folding, full suspension) and current models like the Load. I don’t think it’s trivial to put together the Load.
To the rest of your points, I largely agree. Before ebikes, Rohloff was a niche product, and now on ebikes, it’s still a niche product, not an engineering miracle to integrate with belt+frame. The real reason it isn’t widespread is because 1) most ppl don’t need a Rohloff 2) the big boys at Trek, Specialized undoubtedly took a pass on an additional “service partner” that demands you rebuild a wheel just to send the hub hundreds/thousands of miles to pull out and press in two seals that are external to the hub Itself. I have seen videos posted here on the process without the disclaimer that the end user is unable to obtain the seals or the tools that make the process simple.
EMTB will largely stick with chain/crisper shifting. The R&M price tag of $9-$12k will keep the market small. These are the factors that have precluded commodity status, not that the bits are so difficult to integrate.
I also imagine the R&M press release is largely directed at continental Europe, their principle market. Service is already much better in Europe.