It's all just performative.
Also, the creators of projects can do their part by sharing the praise their projects receive with their contributors.
What other ideas do folks have to encourage joining rather than starting?
Maybe assigning specific "ownership" (responsibility for, overall credit for) of some portion of the project to long time contributors over time?
My argument goes more about the lines of: Some people want to be the starter of a project, disregarding existing, often advanced efforts about the same problem.
Take for example, the bajillion expenses tracker apps. The most reinvented wheel. Do we need yet another one?
To me, it's an ego-driven thing.
Ironically attaching your company to a movement like this will deter people from using it.
The whole reason to pay for software is to offload the liability to a 3rd-party. In simpler words: "As a company, I have this need and I don't want to solve it myself. Also, if I pay someone, I can sue them on contract breach just in case."
The legal part of the liability offload is key in the decision, because it requires ownership.
FOSS doesn't fulfill that requirement, therefore, adopting FOSS means the user owns the liability of using the software. Companies don't need or want more liability than they currently have to, less is better.