I don't know what your issue is apart from maybe being a Synology shill.

Features change in software all the time.

What's so outlandish about someone getting a new unit, it upgrades the software automatically on first run, and then the BTFRS filesystem is available to them use for the array.

You'd either not think twice about it or thank Synology for opening up the new feature for these lower end units.

Taking the feature away like this is the absolute trashiest behaviour.

Your analogy is all wrong, since they advertised these as NOT supporting BTRFS, but they did anyway.

So your analogy should be "Car commercial showed a slow but practical car, you buy the car and it turns out to have high performance and can zoom around corners, then a year later a software update forbids you from driving on the road to your house that has a high speed limit so now you can't get home"

I still don’t think the analogy captures the reality of the situation. I’d argue it’s more like buying a car that advertised room for five passengers, but when it’s delivered your discover a third row giving you enough room for your entire family of seven. Until you take it in for an oil change, when they lock your kids in the trunk and try to sell you an SUV.

There's an underlying assumption that btrfs support on those devices was actually production level stable and ready for use.

(I know btrfs on ARM wasn't really all that great at times.)

How horrible it would be if commercials had to be truthful.

There's a theory that all adverts, that are not simply information are economic loss. This presumes that vanity has no economic value. How can you legislate when people want to be lied to.