Clearly these are non-trivial trade-offs, but I think using third parties is not an either or question. Depending on the app and the type of third-party service, you may be able to make design choices that allow your systems to survive a third-party outage for a while.
E.g., a hospital could keep recent patient data on-site and sync it up with the central cloud service as and when that service becomes available. Not all systems need to be linked in real time. Sometimes it makes sense to create buffers.
But the downside is that syncing things asynchronously creates complexity that itself can be the cause of outages or worse data corruption.
I guess it's a decision that can only be made on a case by case basis.
E.g., a hospital could keep recent patient data on-site and sync it up with the central cloud service as and when that service becomes available. Not all systems need to be linked in real time. Sometimes it makes sense to create buffers.
But the downside is that syncing things asynchronously creates complexity that itself can be the cause of outages or worse data corruption.
I guess it's a decision that can only be made on a case by case basis.