It matters because as a developer I'll get support requests from users who claim that my software has issues, even when the root cause is unrelated to my code. If I explicitly document that I support a single way of deploying the software, and that way is a self-contained artifact with all the required runtime dependencies, which was previously thoroughly tested in my CI pipeline, then I can expect far less support requests from users.

Again, this matters a lot to smaller projects and teams. Larger projects have the resources to offer extended support for various environments and deployment procedures, but smaller ones don't have this luxury. A flood of support requests can lead to exhaustion, demotivation, and burnout, especially in open source projects and those without a profitable business model. Charging for support wouldn't fix this if the team simply doesn't have the bandwidth to address each request.