Consider the alternative - two programmers make a quick decision over slack, then they both just get to work heads down building for 2 weeks. Say they run into a big issue and realize they have to throw that work away and start again. They just wasted ~160 developer hours of time. Alternatively if they had just scheduled that 1-hour meeting up-front with 3 other people who have complementary experience they might have caught this at the beginning and the meeting would only waste 5 hours (to be conservative, lets say 10 hours since the meeting might take each person out of their flow for an extra hour. Though in my experience if the meeting is mostly a brainstorm about the thing I'm working on, it's just as likely to do the opposite where I go from a vague dread of how much there is to do to being excited and having concrete first steps to jump into).
If they had done this for 15 separate projects, 14 times that meeting could actually have been a waste of time, but on the 15th project they saved all this time and they'd still come out net ahead due to the meetings.
What makes this even more pernicious is that there's such a huge discrepancy in possible time wasted, but depending on personal preference it might feel very different to the people involved. For "hacker" or builder types, any meeting at all might feel like a brutal waste of time even if it saves time in the long run, they'd personally rather waste a few days building the wrong thing than sit in a bunch of meetings. But manager types can take this to the other extreme, they feel productive in meetings and end up scheduling too many of them. As always finding a good middle ground is important.