Totally agree. I made a post, around this time last year, helping someone with this issue (see below):
I think when we are new to Keyboard Maestro, we are enamored with dropping images in that image well. It’s great for quick testing, for a temporary macro or if you don’t have many macros but if it’s permanent, the file path is the way to go. Being that I still have a 2014 iMac, at this time, performance is all I care about. This technique keeps my plist small and manageable.