Isn't there a "throat to choke" aspect of this as well? While not actual indemnification, leveraging a cloud vendor at least allows for a "but AWS/Google/Azure" was down response to your customers. And cost offsets can come into play as well in the event of a failure, or even missing an SLA, in some cases. You don't get that when you roll your own.
Not to mention certain, tested disaster workflows are available such as global tables/databases/etc., alternate region backups.
If your solution is not mission/legal critical, and outages are simply "uncomfortable" then rolling-your-own seems a viable alternative. But, as your customer base grows in size/maturity/ the costs can start to look a little less important. You just bill it through to the end customer.
Not to mention certain, tested disaster workflows are available such as global tables/databases/etc., alternate region backups.
If your solution is not mission/legal critical, and outages are simply "uncomfortable" then rolling-your-own seems a viable alternative. But, as your customer base grows in size/maturity/ the costs can start to look a little less important. You just bill it through to the end customer.