I think that's intentional. The post is a signpost to a place where it is intended to have a concentrated technical discussion on a specialist topic. A specialist place where we can if necessary discuss 40 different subjects, each with their own thread and no confusion about what we're trying to discuss in that thread. Yet still fully open to anybody who cares to join it.
If replies were allowed to the signpost, it would rapidly degenerate into umpteen different subjects being discussed higgledy piggledy in the same thread, leading to the similar mess that we already have with half of the posts in Announcements.
Allowing replies to the signpost doesn't make sense. If you have a technical contribution or functional request relating to the community platform, it should be in the platform discussion, not somewhere else.