I didn’t mention it because I was trying to save anyone any money. I just thought it important that for those who may not know, to clarify that you don’t have to have them. I never have an issue with the wheel moving freely, unless I want it to. Depends on how far you back the nuts off. I also use modified dropout adjustment screws as set stops. so setting my wheel back and adjusting tension is so simple, I could no joke, probably do it with my eyes closed. But that’s the difference right there. Every time I set my wheel back in, it’s not a ‘start from scratch’ scenario for chain tension. My wheel slots back in the same position, and I have the same tension, every time. I just have to remember to set my crank position beforehand. For my setup, having spacers would literally only change how far I back the nuts off.