I think you may be underestimating the amount of people who would buy the easy sollution. I've been part of a makerspace where we've tinkered with 3D printers since before it was cool. I still have a Bambu Lab printer myself because it's the "iPhone" of 3D printers that just works out of the box. I used to have a Linux laptop and now I have a MacBook because it's easy.

If I were to buy a NAS it'd be the "iPhone" NAS because it was easy. Though I don't think your prediction for Synology is wrong. I'd certainly pick the one that didn't previously try to push their own HDD's.