I've made many business cases for internally-built SaaS tools, and they always rest on the idea that our probability of success is higher if we staff a team and build the _exact thing_ we need versus purchasing from a vendor and attempting an integration into our business.

It's far more challenging to win the 'build' argument on a cost savings approach, because even the least-savvy CIO/CTO understands that the the price of the vendor software is a proof point grounded in the difficulty for other firms to build these capabilities themselves. If there's merit to these claims, the first evidence we'll see is certain domains of enterprise software (like everything Atlassian does) getting more and more crowded, and less and less expensive, as the difficulty of competing with a tier-1 software provider drops and small shops spring up to challenge the incumbents.