Several people have given examples of how clothes can be ruined, so I'm not sure why you are finding it so difficult to grasp that someone could ruin other family members' clothing. Having expensive pieces of clothing completely ruined by someone else doing the laundry incorrectly is something that I think most people would be upset by.
You must have a different system. (Do most people even have a separate "machine wash items" basket?) In our house, sorting and checking pockets is part of the task of doing the laundry. So, yes, it would be the fault of the clothing washer for failing to do so.
I'm really not understanding the last sentence. What do you mean by "saving them from themselves"? Do you mean that I should purposely leave items in my spouse's pocket, run it through the washer and dryer (ruining everyone's clothing that was in that load of wash and making a huge mess) just to teach him a lesson?
I feel like if you have something that can't be machine washed, don't put it with clothes items that are going to be machine washed. If something must be hand washed, don't put it with machine washed items.
I feel like it is up to the person who put the clothes in a basket to be washed to ensure it is ready to be washed. But if the household rules are that the washer ensures, there is no reason anyone's spouse can't be trusted to do the job.
As for save them from themselves. I think too many spouses just won't let their spouse do a task because they need to control the task.
I have mentioned having the chores conversation so maybe everyone with the don't touch the laundry rules have had the conversation.
As for the saving them from themselves. I think too many spouses do too much because they feel like or have been led to believe their spouse can't do something. In this case we are talking about laundry. Every adult should know how to wash, dry, fold, and even iron clothes. It is a basic life skill.
One day, one in the marriage will die first. Will the survivor be able to cope?
My wife's uncle struggled for years after his wife died because she did everything for him. He had no idea how to wash dishes, wash clothes, cook, virtually any daily life task.
My grandmother struggled for years after her husband died because he did everything for her. She had no idea how to wash dishes, wash clothes, cook, virtually any daily life task.
While their spouses were alive, he felt like a King and she like a Princess. It turned out that their spouses did them no favor by not allowing them to do and learn.