There's a world of difference between going "hello ("I hope I'm not interrupting" if you want to be courteous, maybe followed up by "I'm foo, what's your name? nice to meet you!"), what did you think of that talk" sitting in front of me or with some space next to me and leaving if I say I'm busy, compared to sitting right next to me with my thigh touching yours going "are you busy working? well whatever, you should check this out! and I'm going to keep talking to you!"

I don't mind the former at all in almost any situation, even if they ignored cues due to the nature of the event - being nice and respecting other people makes it okay and a few people did that just fine! I had to deal with the latter. It's the unwanted physical contact after interrupting without a care that's the problem. I have a sneaking suspicion most people don't want to be on the receiving end of that at a tech event, period, as it's (respectively) uncomfortable and rude. Or do people normally sit close enough to touch a stranger without an introduction and I'm making a big fuss about nothing?

With that out of the way, sure, I agree tech events are about socializing. I normally like socializing. I did socialize. I went to the event to go say hi to a couple people, watch the talks, maybe ask a question of the speakers in person, and then sat in a corner to wait for my fiancé to finish talking to friends...because I was tired and had a non-contagious but unpredictable cough from bronchitis and asthma flareups that would rear its ugly head if I talked for more than a couple sentences. So my lesson is learned. I'll just not even present an opportunity for people to creep?