decisions as barriers to entry
I've been hearing a lot about Mastodon for a while and thought I'd look around, see if I know anyone there, see what it's like, see if it seems to work better than Twitter... and the first step is to choose a host community/server, from dozens of options. The options are grouped into categories like "Tech" and "Arts" and "Activism" and there's also "General" and "Regional". None of the regional offerings are my region, so I browsed General and Tech.
All of the communities have names and short blurbs. Some sound serious and some sound less-so. Mastodon is a Twitter-like social network, so -- unlike topic-focused Q&A sites, subreddits, forums, etc -- one should expect people to bring their "whole selves". That is, a person on a tech server is likely to also post about food and hobbies and world events and cats. From the outside, I can't tell whether the mindset of the Mastodon-verse it "well yeah, duh, the server you choose is really just a loose starting point because you need to start somewhere" or if there's more of a presumption that you'll stay on-topic (more like Reddit than Twitter, for example).
A selling point of Mastodon is that it's distributed, not centrally-managed; anybody is free to set up an instance and set the rules for that instance. One considering options might reasonably want to know what those rules are -- how will this instance be moderated? But I see no links to such things. Many instances also require you to request access, which further deters the casually curious.
I guess the model is that you go where your friends are -- you know someone who knows someone who knows someone with a server and you join and you make connections from there. That's a valid and oft-used model, though I wasn't expecting it here.

no subject
I have had an anonymous account on Mastodon for a few years now, but have not used it much (in part because I decided to be anonymous when I started the account, in part because many people I was interested in following were on Twitter, where I spend more time).
I suspect the distributed nature of Mastodon means "it depends." There is, I think, a "local timeline" that shares the public posts on the server you choose, but… I think I mainly used that for finding users to follow. So… a server with interests that align with yours does have a benefit.
When it comes to the rules, I'm guessing you're coming from the directory from joinmastodon.org - When you click the "join" button, it takes you to the page where you can join. And above the "JOIN NOW" button, there is a checkbox, and next to it is a link to the server rules. Those also (on the ones I looked at) have information about which servers they don't federate with and why.
I think there are probably three main reasons for servers to request access (but I'm mostly guessing in what follows): 1. to slow the surge of new users to a level that the instance can support (especially if the bill for the server hosting is footed by one person or by donations and especially in the wake of Twitter's ownership news), 2. because some instances are set up to avoid some of the harassment and other issues people experienced on Twitter, and 3. because some people want a server that has only people like them.
One other thing to be aware of: on Mastodon (like email), your server is part of the "address" so on Mastodon, we wouldn't be
@outofwaterand@cellio, but@outofwater@myserver.xyzand@cellio@yourserver.abcSo, if you aren't comfortable with a given server's name being visible whenever you share, you might choose another server for your account.no subject
Mastedon
Re: Mastedon
Likewise -- I'm not quitting Twitter, but I don't want to have all my eggs in one basket, either. When LJ got bad it got bad very quickly and lots of people were scrambling to get set up here (and scrambling to figure out that DW was the place to land). I'd like to try to learn from that experience. :-)