And, really, the "hallway track" is the value of going to conferences. For the most part, if someone just goes to a conference to sit in breakout sessions, they're probably better off just watching video of the sessions (if they were filmed) or a webinar version of the content.
Virtual events are fine, as are watching videos. (In fact, for bigger events, I'll often watch the keynotes from my hotel room rather than packing myself into a room with 10,000 of my closest friends so I can watch the distant speaker projected on the screen.)
But it's a small subset of the experience of attending live.
When people make arguments like "taxes should be higher" or "air travel should be more expensive", they almost always mean "for other people".
People need to eat their own cooking or they instantly lose all credibility, even when the facts are on their side.
It could be viewed as an investment in future lower emissions, the same way spending money on R&D today can improve profits in the future.
Even voluntary and cooperative solutions would benefit from the type of coordination an in-person conference affords.
Also, it’s really hard to live in the modern world without using fossil fuel-based comforts. You can criticize air travel and still travel to a climate conference. It doesn’t make climate change any less real. You can maybe argue that people are hypocrites, but so what? The ice caps don’t give a shit. And maybe that meeting of scientists in-person is what it takes to fix a really big global problem. Flying to Asia every year for a vacation definitely won’t do that, though.
Every Hollywood actor demanding we take action on climate change while flying around in a private jet weakens the argument for real action on climate change. It makes the issue look like a vanity cause even though it's not.
You see the same thing on taxes. You've got guys like Bernie Sanders out there demanding we all pay more taxes while he himself has a very low rate of charitable giving by most standards. He could also opt to voluntarily pay more taxes right now. Of course he doesn't, which again undercuts any broader point he may have.
Human beings are hardwired to be turned off by hypocrisy.
I really think we should be working to change this - conferences are huge wastes of resources IMHO. I usually see a handful of inspiring talks, which could just as easily have been delivered as webinars (which would also allow asynchronous viewing, involving a wider potential audience).
Then again, I'm antisocial and terrible at "networking", so those aspects of conferences don't really appeal to me.