I wouldn't quite go so far, but I don't think piecewise enterprise SaaS makes sense. The whole model of having dozens of interacting SaaS pieces, any of which make change APIs, have a bug, or go under any day has peaked.

I'm okay relying on AWS.

I'm not okay having one company handle email, another columnar database, another tabular database, another map-reduce, another streaming / logging, and so on. I understand why each of those might be better than their AWS counterpart, but for business continuity or for security, it's a train wreck.

I'm usually okay relying on hosted versions of open source platforms, since if something goes very bad, I can move over to hosting them myself. Even there, I hesitate with things really central to continuing operations. But for the 95% of other stuff, I find something like hosted postgresql or redis to be most robust.

A company specializing in redis will beat my IT staff. On the other hand, it's low-risk. A lot of companies disappear in a few weeks, but it's rare that they disappear overnight.