Before dry cleaning all clothes would be wet wash safe.

I understand why one would make this assumption, but it is not quite correct. The idea that outer clothing needs to be easily washable is fairly modern: for a very long time, people would mainly wash underwear (underwear being much more extensive than today, covering more of the body and protecting the clothing), with outer clothing being washed less often or not at all, depending on the material, apart from very informal working clothes. "Wash dress" or "tub dress" was used to describe women's clothing that could actually be dropped in a tub of water and washed, because that was the exception to the rule. Wool, which was much more common in daily wear in the past and which could not be wet cleaned, was generally just brushed off with clothes brushes. Additionally, prior to the invention and popularization of the washing machine, washing clothes involved spending a day on laundry at home, having your servants spend a day on laundry at home, or sending all the clothing out to be laundered, all of which are an expense of resources that could be spent elsewhere.

Dry cleaning - washing with solvents rather than soapy water - allowed fabrics like wool to be laundered rather than just brushed down, getting dirt out rather than just off.