If you look at companies like Red Hat, and Nextcloud, neither of these companies sold proprietary versions of their software. Red Hat sold licensed versions of their software, but they were always FLOSS.
Nextcloud's CEO talks about how selling a proprietary version of your code is bad for your customers and puts your company into a Catch 22 with itself. "Do we add this feature to the 'Community' or 'Enterprise' version?" or worse "What do we do when someone makes a FLOSS plugin that competes or is better than our internal version of the same functionality?"
There's a huge need for a good chat system to compete with the likes of Slack, but Matrix has bitten me several times and I don't trust it. In an alternate universe, they could have made Matrix work well for all levels of users and then sold customization and B2B deals with their customers leveraging the community, which has always wanted Matrix to succeed.
As for it being the best of both worlds, it depends what best means.
A company that wants to make a lot of money won't do well with this model. It's a slow growth model requiring a lot of hands on work that requires customers who are paying for features and custom installations.
It's labor intensive work that's quite the opposite of the proprietary software model, which has traditionally had a lot in common with the publishing or entertainment industry. Write a book, get paid for it for years.
I thought this was Zulip?
More importantly, Red Hat was very profitable even when CentOS was a drop in replacement.
Matrix servers (and web servers and mail servers etc) are not as complex - and if anything you want incentives to make them less complex, not more. And the better job you do of making them easy to admin and support (ie the more scalable and stable they are), the less reason there is to pay the upstream for support but some system integrator instead.
Just my perspective but I think this was also perhaps a product of the time when Red Hat really started growing, back when linux was a little more rough around the edges. These days it seems linux has enough polish that some (many?) corporations are happy to just use off the shelf ubuntu and call it a day and hope nothing breaks too badly.
I think it has dawned on people that it is impossible to avoid using open source.
0: https://medium.com/@gordon.messmer/in-favor-of-centos-stream...
CentOS started as a fork, and new forks exist now.