The issue is that creating such a system creates quite some time, especially a proper one. You have to create the Server Plugin, a Server for the Lobby Handling with Websockets and a proper Frontend. While that is certainly possible it requires quite some time and will be most likely wasted time once the matchmaking is coming. If that woudn't be the case I would certainly say "Hell yes, lets do it", but like that?

The second thing is that I had the image that most people are not really willing to donate. To host such a site you need way more than a 5€ VPS, and a proper dedicated server is starting at 60€+ per month, so the programmer who invested shit loads of time also had to pay for the hosting. And subscriptions are most likely really hated in the TF2 Community after what I have seen in the TF2C Advanced Lobby stuff, tons of comments "Why should I pay for something I get somewhere else for free?".