I have never been to an academic conference where I have gotten anything from the talk that I couldn't have gotten from reading the paper. The advantage to a conference is that I have easy access to the author so that I can ask questions, discuss similar ideas or even just network. Non-academic conferences serve a similar purpose. Yes, you could just read a blog post. However, if you are looking to explore ideas with people that have an interesting way of thinking, or if you want to pick someone's brains, or if you just want to network, conferences are extremely useful. There are lots of people who do normal every day practical work that I would love to talk to. There is no need for the excuse to get together to be an academic talk.
This is a fair point. But I think, and this is a large generalisation, that the answers to questions at an academic conference will be far more in-depth and interesting than those at other confs.
Not only that, but the calibre of questions asked is likely to be higher, resulting in better answers too. If the answer could be given as a comment reply on an equally banal blogpost level talk, then was the ticket price really worth the opportunity to ask the question face-to-face? I'd pay money to ask the leading expert at x university in machine learning a question. The leading "expert" in ClownJS? Not so much.
