@evacide At least for some of those other platforms, it may a sign they're dying from lack of non-automated participation.
I noticed after I came to Mastodon, it soon became the only place people would respond, even when the same post was made on the Birb too. I eventually gave up cross-posting to the Birb because there were no longer signs of life there. Since you have a much bigger audience, that's probably why it took you longer to notice.
@KO6YQ Twitter is not one of the platforms that I post to and therefor not part of the observation I was making.