Worrying? Amiga is not an entirely healthy platform and it is probably more divided than anything reasonable mainstream.
Both macOS and Windows are single platform (or two for Windows if you count 32 and 64 bit, it is in a transition period).
For UNIX we have several *BSD and Linux variants. They either need massive infrastructure to deliver binaries (Linux), or resort to source distributions (*BSD) for add-on software.
Amiga has four different platforms, and one of them (AROS) supports multiple architectures. Additionally, we have a lots of infighting between the Amiga platform supporters. Add to this that 3 out of 4 Amiga platforms rely on hidden sources, and given the overall sizes of macOS, Windows and UNIX market shares compared to the Amiga family, well I think you know this.
The Amiga forums I have seen either are kind of devoted to a single strain (but they often list different sub-forums) or as with amigaworld.net which seems to sport a variation of different platform users (but leaning towards OS4), people just do not seem to do much development on either platform. We are more like users and dreamers. Kind of what Wawa said.
Perhaps you should pick your favourite forum, like eab which seems to be the most active one. Ask them if they want to create a sub-forum for cross-platform development. I think the Amiga forums may not have thought of it in this angle. Otherwise just go ahead in whatever place you might seem happy with. Do not worry, just do (try) it.