> If you don't think this is true, why do you think they released it under an OSS license?
I'm not familiar with Hashicorp's motivations for using a permissive license, and I believe this is tangential to the point being discussed (attributing Hashicorps' products success simply to being open source vs being useful software that solved problems in a novel way).
But I do know sometimes software is open-sourced (or at least made source-available) without accepting changes upstream at all, which clearly isn't done for reasons of wanting contributions. Or other times, authors will accept some outside contributions, but aren't outwardly seeking or encouraging them.
Nothing in any FOSS license requires the author to accept changes. Having the source be available is beneficial on its own for reasons of adoption and allowing users to trust the software.
> Reciprocating would mean allowing others to build businesses on software they have also contributed to.
Nothing prevents these companies from doing so via a fork of the last FOSS-licensed version, which is exactly what they've done, and is fine legally.
> It's not all their own work.
They own it. This is clear cut. It's copyrighted and has a CLA for third party contributions.
> it's about screwing over and denying that right to others
What "right" is that exactly, and what makes it a "right"? Legally you can't just make up "rights" based on feelings and assumptions.
Absolutely nothing in these permissive licenses requires future versions of the work to keep the same license.
> If it's useful high-quality software, history shows us that such projects continue to thrive regardless of the status of the 'creator' (e.g. Jenkins)
No, history shows it's quite a mixed bag, for example OpenSolaris/illumos has a minuscule amount of marketshare/mindshare compared to Solaris's heyday.
Also, Hashicorp very clearly created Vault, Terraform, etc and putting creator in quotes is a really gross way to minimize their clear achievement in designing useful and novel software that previously did not exist, and would not have existed if not for their efforts.