Initialize(true)
orphans the entire SkeletonAnimation system and creates a new one every time you call it. This will generate garbage and allocate memory every time it's called and is totally unnecessary. (That's like rebooting your computer every time you need to open a new browser tab.)
I think you want SkeletonAnimation.skeleton.SetSlotsToSetupPose();
If they only like it because it's more visible in the Dopesheet, we should probably improve the dopesheet.
I have suggested to Nate a few times before that attachment keys in the dopesheet should show what attachment they're switching to. He hasn't gotten around to it.
Regardless, one slot per frame is inefficient, makes a mess in the dopesheet and is prone to errors, and you lose the ability to color or change the blend mode of that set of images in one place.