those don't convey nonverbal communication, and they are so unstructured that they interrupt too frequently
there's something positive about setting time on the calendar and then sitting down with someone (or a group of people) to talk about a specific subject that we've all prepared for. yes, you can do that with Zoom, but then you miss the ability to speak simultaneously and the body language / nonverbal.
not everything should be a meeting, but not everything should be IM / phone calls either. being able to mix and match is what makes in-person somewhat positive (even if I personally prefer a hybrid model)