Hello Internet, over all those years of being into open-source game development I just have to tell someone my experiences with that.
Let's just start with the biggest problem right ahead and the biggest problem with the nonexistent open-source game development community is its nonexistentness and the biggest problem with nonexistent things is, that they don't exist.
On a second look I think, it could also have been my fault to assume the nonexistent open-source game development community exists to begin with. To my defense I have to say that there was quite some evidence that the nonexistent open-source game development community exists, like many seeminlgy existing games being developed as well as websites dedicated to that and of course many people seemingly developing open-source games. However now after almost 6 years of being into game development, I can pretty safely say to have never met a serious active open-source game developer. Before people now go nitpicking on my definition of what is serious and what is active, I want to try to give an easy explanation for that, serious means that someone seriously tries to accomplish anything and active means, that he is currently actively trying to seriously accomplish anything, or even easier explanation it has to be an existing open-source game developer, since only an existing open-source game developer can develop existing open-source games, while a nonexistent open-source game developer can only develop nonexistent open-source games.
Sadly there exist many nonexistent open-source game developers, who develop even more nonexistent open-source games, which may give the impression to outsiders, that they are actively existent open-source game developers, but as an insider you will quickly find out that they do not exist. How I'm so certain, they do not exist? Well I never met them, it is that simply. One could argue, that I have not searched enough and I may meet one some day, but I have to say I searched very well and found many regular game developers and I'm able to interact with them almost daily and talk about real existing game development, so even if the open-source game developers exist, they must be of such small quantity, that they are basically nonexistent.
My views may sound a bit radical and of course it was a bit exaggerated, in reality there are of course exceptions. I indeed did meet some existent open-source game developers from time to time, but as said they were of very small quantity and not very active overall and most of them quickly abandoned their (mostly nonexistent) game projects. So yes there may be small exceptions, but generally I think I'm correct with my conclusions.
I also do not think I was delusional when starting doing open-source game development, since I started it, since there was nobody doing an up to date 3D shooter that is not a ripoff of Quake over and over again. So the main reason I got into existent open-source game development was, that at least as I thought in my niche open-source game development was nonexistent, but later it turned out I was wrong with my assumptions, since not only did open-source game development not exist in my niche, but it did not seem to exist in total.
Somewhere inbetween those experiences I also joined some communities of nonexistent open-source game developers developing nonexistent open-source games, but they quickly censored and banned me for doing real existent open-source game development, they were probably just scared since real existent projects are superior to nonexistent projects which cannot prevail against existent projects, but that is another story.