But I have to wonder what the hell they were doing. What is coordination other than talking to each other and showing each other things? In my opinion this is much easier via calls.
However, my actual job requires a lot of communication - some of it is perfectly ok to do remotely via calls etc, but a significant portion of my job involves ad-hoc discussions, whiteboarding, throwing ideas around and coming up with a solution to a problem that is highly specific to our domain. This is the problem area, for me - I've found no combination of tools that adequately plugs the gaps that remote working has left in our ability to have those kinds of conversations / design sessions - and certainly no combination that everyone 'gels' with.
For me, it's a major issue. Productivity in those area has absolutely tanked. Pre-planned, pre-determined work is generally ok, but the more informal side of things - which is actually probably around 50% of what we actually need to do in order to keep things moving, has gone to hell, which now means we ask people to come in at least a few days a week to try to plug the gaps.
If this was a reasonable argument, nobody would ever have any issues!
Your anecdote is not data - it's just an anecdote.