How would you compare Elixir with Kotlin (or similar) in terms ease of use and efficiency?

ActivityPub has been around for 8 years, and IMO, the Fediverse is not evolving. It is not federating the way ActivityPub was designed for.

From this I thought you are referring to the fedi platforms in general. I saw later you wrote specifically about Lemmy; so ok.
Still, my example shows that the Fediverse is evolving (even if it might be slow). Lemmy and Mastodon might be the biggest platforms out there, but they might not be the ultimate prestige examples of our network.

They said Diaspora never gained support, not Friendica.

I can’t show you directly, as fedia.io requires login to access the platform (scraper protection), but I was able to open the channel by searching for their handle, the page showed up videos (also recent ones) and the video-posts had comments. The page show the channel-logo and every post had the thumbnail of the video.
One click on the title when you have to post open, and it will open the original page in a new tab, which then can play the video. Even better: Mbin automatically inserts the embedded viewer for the posted video, so you don’t even have to leave fedia.

So please don’t draw conclusions from Lemmy to all fedi projects.

And for some fedi projects even a handful of regular contributors would be much.

or hate for other platforms?

I contribute to Mbin out of passion for the Fediverse and the idea Mbin is build upon. But hate against bigtech is also a factor here and there :D