I was a SWAT FTO for my team. I can think of a couple guys who were great street cops but couldn’t do SWAT stuff even after they got a lot of extra training.
It's not the idea of sashes themselves that were derided. Having a "CCW" sash was seen as the equivalent of CCW badges, though it was a good attempt to be identifiable without "Sheep Dogging Hard" Having a sash that says something on it other than or less instantly recognizable than "Police" is a fail regardless. Though studies have clearly shown Sashes are much more recognizable under stress than badges, including badges on neck chains, if they have agency names, acronyms or anything other than "police" the recognition rate plummets.