I think another problem is that people who attend online conferences tend to squeeze them into their normal working day, thus only give half their attention, and maybe rely on watching recordings of the talks later to fill in the bits they miss?
How many people who've "attended" UKNOF meetings through the live streams have actually put aside their normal work in order to be able to focus 100% on the talks? And, even when they are there in person, I see many people with laptops who seem far too busy doing things to actually give the talks their undivided attention!
