I wasn't trolling, my response was geniune and I was disappointed. My comment wasn't clear, please don't take it the wrong way.
This was when kbin.social was REALLY active. IIRC probably around June 2023? When Ernest was still active maintaining the kbin.social instance. The Mastodon instance I was talking about is mastodon.art. And if I search around, I'm still right that the instance seems to REALLY like to defederate without valid reason, I will link some thread that talks about this below [^1].
I wrote about the detail of this in kbin.social, but kbin.social is no longer active so I'll admit I kind of forgot the detail.
As far as I remember the reasoning stated in mastodon.art federation status is that "right wing" or something along that, at the time. I knew at that time that was wrong. I don't really care about right wing or left wing (I am just a Southeast Asian, that dichotomy of politics is kinda unrelatable to me, but that's topic for another time). But kbin.social was definitely not "right wing", in fact it was one of the "leftist" place I've seen on the internet.
Even then, the reasoning feels kinda off to me, other than the fact that it wasn't true, why would you defederate instance over difference of opinion? If the instance was spamming your agenda to your instance then it's probably justifiable. But it clearly wasn't at the time. [^2]
And regarding "keeping people away from fediverse", I was talking about the UX of fediverse.
That time, I wanted to follow someone from mastodon.art as said person is an artist I really like that was disappointed with Twitter and trying out several alternative social medias. Somehow they chose to join mastodon.art. I was happy and wanted to follow said artist. I tried following them but I remember I had a hard time doing so.
Turns out my instance was defederated.
At this point, I'm sure most non-tech-savvy user would have given up. But I still tried following it anyway. I tried creating mastodon.art account, and, it turns out, mastodon.art sign up requires approval. At that point, I kinda given up. It's gonna take lots of time until it gets approved, so why bother?
The admin behavior somehow actually made me doubt that I will get approved too (though to be fair, it ended up being approved). And then, why would I use the mastodon.art account, when the instance is defederate-happy, making it actually hard to discover another artist to follow (in an app that already have some problem with discoverability)?
Since then I started using less and less fediverse. I was kind of annoyed by this experience.
Defederation perhaps is necessary.
But it is prone to abuse by admins. And that degrades user's experience.
[^1]: https://beehaw.org/post/6853561 , https://lemmy.dbzer0.com/post/4695219
[^2]: Going off topic for a minute, this is yet another part that I don't like about some folks in the fediverse. It seems similar to my observation of US domestic politics. They just want to stay in their own bubble and doesn't want to compromise and hang out with people with different opinion. That isn't how I was taught to live. I hang out with people with different beliefs--be it religion, politics, ethnics groups, etc-- all the time. These kinds of behavior made it hard to have some actual discussion. Those people lacks nuance.
Indonesian here too. Same I am as confused too. It makes political discourse here looks good