> There is no reliable way for a dating app to only serve users non-committal matches for example

While that certainly sounds difficult, it sounds feasible for e.g. Facebook.

> The thought experiment I usually pose is to ask what you think a free, open source, and community supported dating app would change. The answer is "not much".

That sounds more like a framing problem. If the ultimate goal is promoting long-lasting new romantic relationships, and it's developed without any profit motive, I'd imagine a general social network that primarily organizes in-person social gatherings.