I think so, following this logic:

You have a FOSS tool that's awesome to work with. By yourself, you can take the time to set it up and learn how to maintain and use it. It's actually the case most of the time.

If this tool is interesting/useful enough to attract companies, they don't always have or want to have a service/person to set up, configure, maintain and debug this tool.

In that sense, companies making the FOSS tool can sell active support, maintenance and hosting, and I think it's perfectly fair here.