People spend thousands to go to a conference and the stated benefit is to hear a few talks that are definitely recorded and to have a handful of useful conversations.
Let's be honest: many people at conferences just see them as a way to have the company pay for you to get out of the office and go on a semi-vacation. I know I've gone to things with that mindset before.
Don't get me wrong it's not the events that are the issue, it's how far we travel to them. I'm sure 90% of the benefit could be had by going to local meetups and watching the big conferences online.