In my mind, the relevant distinction is that a conference is broader than the "hand-curated list". If you had a conference and only 12 people showed up, I'd still be willing to consider it a conference. But when I ask some friends if they want to meet up after work and talk shop over beers, I'm not organizing a conference.
To be clear: literally speaking, "conference" is basically a useless word: it just means folks getting together and talking. Practically speaking, if we're going to use "conference" to mean any time multiple people talk to each other, the word stops being useful for communication, because when it's used it doesn't convey any information.
"Conference" has always meant any formal(-ish) gathering of people talking together. From OED: a formal meeting for discussion.
"he gathered all the men around the table for a conference"
It's "convention" that denotes "large conference". (OED, again: a large meeting or conference, especially of members of a political party or a particular profession)
I specifically noted in my comment that I understand the literal meaning of the word can be applied to basically any group of people who meet. My point is that an article about "How to Host or Attend a Tiny Conference" holds a very different connotation than "they gathered all the people around the table for a conference".
I was agreeing and expounding about the literal meaning and how easily it is to confuse "conference" and "convention". It seems like a lot of people's connotations in the debates here confound "conference" and "convention". The existence of "convention" for meaning "large conference" as size being a key factor would also seem to imply a usefulness in the term "small conference" or "tiny conference".
I think the remaining debate is about semantic distinctions in individual connotations eluded to in the "formal" part of the literal definition of "conference". To many here it seems like open enrollment is a formality they expect, though an interesting argument here would be that invite-only is more generally/historically considered the more "formal" in connotation. It's an interesting assumption to question in people's connotations of what "conference" means.
