The difficulty that some projects have is that the majority of their
contributions come from a single company, who makes their money by
selling an "enhanced" version of the OS project, a cloud version and/or
support. As a result anyone (not just Amazon) offering that system as a
service will divert customers from them, leading to a reduced income or
ultimately bankruptcy. There have therefore been attempts to restrict
what you are able to use some projects for, to prevent such competition
- whether this is a good or bad thing is a matter for debate.
Prometheus is more similar to Linux in that while a number of companies
do contribute, none of them own Prometheus (legally that is the CNCF, a
non-profit foundation) and therefore they are all on equal footing -
various people do offer cloud hosted Prometheus systems, but none of
them are competing with the "Prometheus company". In addition to company
contributions there are also a healthy number of individual
contributors, which don't suffer from the same financial limitations
(just people being willing to offer their time).
--
Stuart Clark