Your pointless snide comment notwithstanding, they do this quite often when a crew is reaching their HOS limit. However, it can't be done in every circumstance. Maybe the crew was expected to make it before they ran out of hours, but some new delay put them beyond that limit at a point too late to send out a crew before the first one expired. Or maybe the train is traveling away from the crew base, with a similar situation, and they determined that it's easier to hold the train there while the crew caught up to it rather than have it continue further away from the crew that is coming to relieve them (if the train is in a location convenient for the dogcatch crew to access, but moving forward would put the train in some middle-of-nowhere area more difficult to get to them, it makes more sense to stay where they are).
Or, and given the situation around the country right now, a quite likely alternative is that they simply ran out of available crews because staffing is thin, extra board is near or at zero, and delays causing trains to be hours out of their scheduled slot mean that the normal crew rotation doesn't work because the crew that would have taken that train is now needed to take the train in the other direction that the now-hours-late crew was originally supposed to head back on. So you're stuck waiting for someone to get legally rested enough to call them out to send them out. And when you're dealing with a train that only runs 3 days/week, you're already not going to have a very large crew base of conductors & engineers to start with. Add a multi-hour delay, COVID sick calls, and the general staffing shortage affecting many industries throughout the US and the world, and you're going to wind up with little to no margin for error. A few days ago, this resulted in a handful of LD trains being cancelled outright. Here, it results in a delay. Pick your poison.
"Some manager" can't make a crew appear out of thin air, despite what some on here apparently think.