To remove some plugs they may not need any more when remove certain components which they don't want.
Also they cut looms to modify other looms or to make place for a modification to be done on a loom.
I had to cut up 2 looms when changing the engines in my Supra as they were different generation engines. So I had to cut certain plugs from the one and the other and swap them around so everything matches up etc...
Other people will probably have different reasons for cutting up looms aswell...