People who write open source do it for analogous reasons, except the "strategic incentives" are often personal. Those reasons can change quickly when shiny new things appear. There's a wealth of abandoned OSS projects that illustrate this point.

Anyone working on Mesos these days?

That's been my experience as well, and the same applies to groups that own/maintain certain projects, like drools/RHDM. The project/technology owner/maintainer is aligned with corp based on customer size/needs, and that alignment is a function of how much the customers are paying.

If and when a large customer drops out, the entire corp and open source structures can change because the monetization changes. On the plus side, if there's a broad customer base, this is less likely to happen.

When will this not be the case? Most companies use a lot of open source, in order to ship quickly. I suppose the thesis of main link is, that's no less so the case -- but here we are, building UIs with Vue/React/Angular/etc. Tons and tons of open source tech to enable shipping more quickly.