They don't explicitly spell this out, but this is because being a VC is still a job. Even if they're not actually making any deals, management doesn't want to see everyone sitting at a desk scrolling twitter for 8 hours, so instead they do pointless meetings.
Matt Levine had a fun Great Recession story which I cannot find right now, which is that during 2008 in the M&A department at Goldman Sachs everyone still came to work, even though obviously merger and acquisition activity was way down. They would spend every day doing calls and making pitchbooks, all of which went nowhere. Goldman didn't close a deal for a full year. A floor full of people could have just collected a salary and stayed home for 12 months and it would have had an identical outcome.