Obviously some work is synchronous, but it's not an excuse for the norm today, where time wasting is the default.
Most managers are lazy and bad at their jobs, and there is no accountability for that. So they prefer to waste lots and lots of other people's time in exchange for slightly more convenience for themselves.
And yet, still the situation I described can arise for perfectly valid and rational reasons. Like if the context required for your 30 seconds of input is difficult to convey quickly - if you’re available on Slack but it takes you 15 minutes to get through all the questions everyone else has already addressed in your absence, then as long as there are 3 people you’re keeping waiting whose time is equal or greater in value to yours it isn’t at all inefficient for you to have been sitting there doing nothing but listening for an hour to get to that point.
Plus, the simple act of receiving information in a meeting is often valuable in itself, even if you as (one) recipient (of possibly many) don’t immediately perceive that value. Again I’ll plug High Output Management, which explains why far better than I can.
All work is not this way (even though some managers pretend it is), and very likely the majority of your work isn't like it (assuming you are a software developer). But some work is like it, and pretending it isn't as about as expensive as gathering people doing asynchronous work into meetings.
(The "what should we do" decisions normally require more synchronous work than "how should we do it", some professions do spend most of their time in the former.)