Water is a great solvent and with agitation for hours with no labor would clean great. Soap just makes it faster. The deepest cleaning methods are abrasive and approach sanding/polishing, like brushes or steel wool or scratchy sponges, and those methods and a rinse will remove anything over time, including the object you’re cleaning. All batch clothes washing uses the fabric rubbing against the rest for friction.
When you dry in the sun, the UV helps with disinfection, not that the idea that sterility is necessary for blankets holds any validity.
https://en.m.wikipedia.org/wiki/Sideshow_(automobile_exhibition)
For anyone else not in the know