Good posts by @GG1 4877 and @Madockawando.
I joined in 1989, just as the uptick in membership was starting. Here's my view on the 2-signature rule.
The dealer from whom I made some of my earliest purchases was an arrogant blowhard (and that's being nice about it), and not very approachable regarding TCA or much of anything else. I read about TCA in CTT and sent a letter (remember those?) inquiring about membership - never got any response, which left a bad taste in my mouth. Started buying from a much friendlier dealer who explained things and told me about local meets (remember those, too?). He and another customer (who didn't know me) signed my application, so there really wasn't any vetting involved.
Reading about the old days of TCA in the 50s and 60s, I understand the idea behind the 2-signature rule, as many transactions were based on item descriptions in letters written between members, so a high level of trust was required. By the time I joined, local meets were common, so I think it had outlived its usefulness.
I've never liked the idea of having to know someone in order to join an organization - strikes me as elitist. I would never join a country club for that very reason. I'm much more in favor of being inclusive and letting a person prove themselves.
Unfortunately, we're losing a lot of local in-person interaction. Our local chapter's meets, which once included dozens of sellers and hundreds of attendees, dwindled down to where the small number of sellers outnumbered the buyers and died out completely about 5 years ago. Most of this was due to demographics, but it was also pushed along by arrogant leadership at the division level.
For much of the 90s and 00s, TCA membership seemed to be very transactional to me. In recent years, there's been more emphasis on relationships, which I think is a good thing, so I'm disturbed by the "I only pay TCA dues so I can go to York and buy stuff" mentality.
End of rant. 
