Every SmartThings customer does, no? Not sure I understand what you mean by “at scale”.
Or are you asking why Samsung continues to sell SmartThings without a backup/restore mechanism?
The lack of backup/restore or migration was discovered 6 years ago and came to more visibility with the release of Hub V2 in Sept 2015. The fact that SmartThings continues to be successful in the market is evidence that consumers don’t take this lack of functionality into account for their purchase decision. So if this is difficult for SmartThings to implement, they seem not to be incentivized.
Is Vera still doing well?
SmartThings is currently the top brand of its class - The question is “define the class”.
If a typical Customer has fewer than 20 devices, and the odds of a failure / reset / upgrade are low, then the statistical “net average effort” required for manual restore is very low.
I’m not making excuses for SmartThings - just speculating as to why this fundamental feature continues to be undelivered after 6 years.
CEO Hawkinson promised (in writing) that it would exist by the end of 2016. He’s no longer CEO - Though only a personal choice, not a consequence of broken promises, since the replacement management team has had years to remediate.