Well I think we are looking at it wrong when we look at it in terms of "easy", "lenient", "difficult" and similar.
What we should focus on is a process that is "exciting", "creative", "interesting", "fun" and things like that.
Like, I joined a bunch of different factions (I've also been a horribly inactive member in almost all, so of course it's my responsibility too), and what it basically is is that you get thrown into a skype chat with some people (half of which you are in other skype chats with), you get a rename pass for a ship and a rank, and you log when people say "log log log" and post reports to gain a higher rank. That's ALL there is as a regular faction member in most factions - some (very few) make an effort out of making it an experience for the player to join and try to promote the player to develop his character; but the majority of factions are just clan-like skype chats, but the members still parade the forum as if they have some god-given legitimacy due to their tag and official status. I think the general recruitment process and the pressure to maintain it due to faction activity requirements (as well as parts of the "faction mentality") create barriers for factions.
That being said, there's a big difference in the number of players in Eve and Disco, that's a good point. But adversely that we are so few players also gives each of us knowledge of what the other players are capable of, even if it is a game without a character sheet and "skills". Say, if Raymond Lister was to announce that he's tired of rocks and is looking for a better contract with a new employer, a lot of factions would be interested due to the reputation that player built up. There'd be an interest in recruiting different players with different strengths in different roles.