I do agree that 'that's dumb', but at the same time neither am I trying to gain acceptance at a table that has been playing Greyhawk for 40 years. I am not a "real fan", and I wouldn't try to present myself as one. As much as possible, I'd try to assume the attitude of a novice, and wait to win my respect from them. And if they asserted, "Look, we've been playing together 40 years. We're not only deep in Greyhawk lore, but we have so much table history together that a new player would be lost.", well, they have a right to keep the gate to their country.
Personal table space and the community writ large are not the same thing. That's been my whole point I don't want to player certain kinds of games. I'm free to pick who I play with or not, but that doesn't mean somebody that doesn't share my pesonal preferences or level of enthusiasm should be made to feel unwelcome at say Gen Con, or here on ENWorld.
I can be a fan of say Star Trek. I'm pretty sure I've seen every ST:TNG episode, I'm not as certain I've seen all of TOS, I know I haven't seen all of DS9, Voyager, or Enterprise. I fore sure haven't seen any Discovery. I've seen all of the movies, an the JJ Abrams reboot (but not the sequels). I read a few novels back in highschool. All of that probably makes a fan of Star Trek. I like it, I think its a great franchise. I can't tell you what Scotty did in episode 37 or whatever. If I asked my dad if he's a fan of Star Trek he'd probably say yes. I'm not sure he's seen anything other than TNG and TOS and the movies up to Star Trek 6, does that make him not a fan because I happen to have seen and read more than him? What I went to a Star Trek convention, I'm not going to dress up, should I be questioned at every turn why I'm there if I'm not in costume?
Yes, but isn't it the first situation that is really relevant? I mean if the person never tries to enter the gate, why does it matter if there is a gate keeper?
Because the gatekeeper can be such an asshat they make the people that are part of a community look bad by association, often because its the loudest person doing the gatekeeping. Additionally, its usually somebody that takes it upon themselves to do this rather than being asked by a community. That's the problem, its an unwanted, unneeded position and jerks take up because they think they know what's need to keep a community "safe".
If you think about it the mods on EN World are gatekeepers of the website and forums. While we as members don't have a say, given that EN World is a private forum itis something we agree to. However, Morrus and Umbran can't just go around the internet declaring people unfit for D&D because they aren't EN World members. That's the kind of behaviour we're talking about. Its not private clubs, or what a fan is, those are all distractions from what I really think Morrus was trying to get at originally: none of us get to make another person feel unwelcome because we think they aren't really a fan, or we're keeping D&D safe from those unwashed heathens that only like watching streaming and don't actually play.
Celebrim, I think you keep conflating the idea of a rules based club/game/organization (with either implicit or explicit rules) with somebody saying, "No you aren't really welcome as a member of any group related to X because you don't meet my perceive criteria." Having rules based criteria for joining a group/club/whatever is fine. Warhammer is a good example, to participate in a tourney you need painted models. However, buying prepainted models or paying somebody to paint them does no less make you a real participant in Warhammer, and I'm willing to be some players that take great pride in their paint jobs would say otherwise.
As for hand lettered card to try it out, other than official tourney play there isn't actually a rule about that, other than other players being jerks to you.