Say what you will about reddit, at least an established subreddit was the place to gather on the topic, ie r/technology etc.

This premise on which your question is based isn’t actually true though. There’s /r/technology and also /r/tech. There’s /r/DnD and also /r/dndnext. As of recently, for some reason there are like 35 nearly identical amitheasshole subreddits with different names.

I feel like what you’re observing is just that reddit communities are mature, people have had time to gravitate to whichever community is more active or has better quality moderation and so there is generally a “winner” sub with more participation because… unless there’s a major problem with the bigger sub it tends to be more interesting than a less well-tracked sub.

Lemmy, in contrast, is still fairly wild-west. Most communities are not very active and have only a few subscribers. If a competing community with an overlapping topic appears, folks are willing to subscribe to it just in case it takes off. If Lemmy continues to retain a healthy number of users, I expect in most cases that consolidation would set in unless there were major differences in moderation policy or something else that splits the community into factions that align across server or community boundaries… and over time you’ll see a similar layout of one or two dominant communities and a long tail of tiny ones that few pay attention to.

It’s not exactly what you’re looking for, but there’s an open-book icon on the right-hand side of line with OP’s username, the community, and the post-time that expands the content. I’m not aware of a setting to auto-expand this option for all posts, but if you’re willing to click that icon you don’t need to leave the feed to see the post content.

It seems likely that an extension or maybe even bookmarklet could auto-expand every post, or of course you could file a github issue to have this be added as an option.

Each instance has a /instances/ url that shows its current federation links at least. It doesn’t tell you its federation config, but you can at least tell if the federation list looks weirdly small or the blocklist looks weirdly big.

• Here’s lemmy.ml: https://lemmy.ml/instances/
• And monero.house where you were surprised at the lack of links: https://monero.house/instances/

And you can see that monero house has a pretty short list in comparison. This is absolutely a page I was scoping out when shopping around for an instance to join. I would also spend some time scrolling through /modlog/ to get a feel for what their moderation was like in practice.

I encountered this while trying to set up my community subscriptions on lemmy.world, which is a very new server and had few people subscribing to remote communities when I joined. Here’s my comment outlining the behavior:

https://lemmy.world/comment/1692

Summarizing:

• Federating with a remote instance does NOT seem to add all it’s communities to your local instance’s list. Immediately after federation, most communities will be missing from /communities/ on the local instance, and keyword searches on the local instance for the community will return no results.
• Searching for a community using its url or bang-prefixed-id causes the local instance to “discover” that particular remote community. It now shows up in /communities and keyword searches.

Also, as others have mentioned, there’s https://browse.feddit.de/ for a distributed community search, though it seems to take some time for new communities to show up there. As an established instance, I also find lemmy.ml’s community search useful for discovering communities even though that’s not where my account is. “Most” big communities have been added to it’s list by someone organically searching for them by bang-id or url.