In a word --- reliability. Self hosting introduces multiple failure modes making it difficult to achieve redundancy and uptime comparable to purpose built and

In a word --- reliability. Self hosting introduces multiple failure modes making it difficult to achieve redundancy and uptime comparable to purpose built and professionally managed cloud infrastructure. Downtime can be a serious blow to many startups. And the more important the service is, the less tolerance clients/customers have for it. For any sort of *business* service, you probably risk losing more than you stand to gain.