> Are you saying that if I'm using D-without-GC, I can use any D library, including ones written with the assumption that there is a GC? If not, how does it not fracture the community?
"Are you saying that if I'm using Rust in the Linux kernel, I can use any Rust library, including ones written with the assumption they will be running in userspace? If not, how does that not fracture the community?"
"Are you saying that if I'm using C++ in an embedded environment without runtime type information and exceptions, I can use any C++ library, including ones written with the assumption they can use RTTI/exceptions? If not, how does that not fracture the community?"
You can make this argument about a lot of languages and particular subsets/restrictions on them that are needed in specific circumstances. If you need to write GC-free code in D you can do it. Yes, it restricts what parts of the library ecosystem you can use, but that's not different from any other langauge that has wide adoption in a wide variety of applications. It turns out that in reality most applications don't need to be GC-free (the massive preponderance of GC languages is indicative of this) and GC makes them much easier and safer to write.
I think most people in the D community are tired of people (especially outsiders) constantly rehashing discussions about GC. It was a much more salient topic before the core language supported no-GC mode, but now that it does it's up to individuals to decide what the cost/benefit analysis is for writing GC vs no-GC code (including the availability of third-party libraries in each mode).