[mikst]

> IT/engineers won’t spend time building and maintaining email servers, we’ll spend $5/month/employee on G Suite and use their time on things that make our products more valuable

In-house email servers are not constrained by the time to build them, but rather by reputation/spam considerations. Sorry, but that's a lucky guess ;-)

> paying for a third party SSO solution for our products and instead using engineering time to build first class integrations between our products and complementary products, because having an artisanal SSO System doesn’t benefit our customers

That's one of vendorlockiest vendor lock out there, which is a very YOLO decision.

The idea that buying stuff is more efficient then building it yourself is at the cornerstone of the modern economic theory, but that's only a theory. In the wilds there's much, much more factors to consider then just comparing cost of building versus cost of buying.

[billyhoffman]

Of course there are more factors. We are not blindly outsourcing everything to services and we are equally not blindly building everything in house. Those factors often come down to core competencies and “best and highest use” of time. These will vary by company. Case in point: lots of companies use highcharts and D3 for charting. why? Because building and maintaining a world class graphing system is not their core business and doesn’t meaningfully advance their business. And outside of a small minority of companies building your own charting from Scratch does not provide a meaningful advantage for your customers or over your competitors.

Deciding what is core and should be in house and what is not is hard and it’s only partially a technology decision. It’s primarily a business/market decision and being able to do those is a mark of a good CTO.