While it is indeed possible to run Home Assistant without any dependence on Nabu Casa infrastructure, Nabu Casa makes using Home Assistant convenient - and that makes people rely on it.
Is there some disclosure statement somewhere regarding what functionality of Nabu Casa user goes out when cloud is sad?
Ideally, these services would keep working even when a vendor like Amazon, Microsoft, or Google (or a smaller one, are having a bad day… and trust me, these bad days happen as we’ve seen most recently with AWS)… but perhaps an easier lower bar, and in good spirit and on-brand would be to publish some info in the form of some plain English “reliability story” somewhere.
For example, optimistically and at some point this could look like:
“… if AWS is borked globally for whatever reason, lots of folks will have a bad day, so will Nabu Casa but your feature {foo} will probably be fine on short order because we can stop publishing AWS specific endpoints in DNS…”
… I realize Nabu Casa is simply too small in terms of actual humans employed, to pull off multi-cloud successfully (ie. you need a good cohesive team of at least 10 qualified people in order to pull off a 24x7 rotation otherwise you get smart creative software engineers dealing with BGP and DNS running scripts over SSH at 3am and that’s a good recipe for burnout …
… also there’s cognitive overload of having to deal with multiple clouds, … even if you have terraform – that just adds a third tool into the mix.