Oxydol
In that incarnation was granulated soap, therefore of course housewives and anyone else doing laundry wanted to see high froth. Mounds of suds have been the indication for ages that there was enough soap in the water to clean.
To an extent soap is it's own water softener. That is because the stuff binds with hard water minerals once you have enough soap in water solution that takes care of that problem the rest is used for cleaning. This is why you can use less soap when laundering with soft water versus hard.
Rinso, Super Suds, Oxydol etc.. were all competing as the "modern" way of laundering/cleaning as they were granulated soap powders. This as opposed to grating or shaving off bits of soap as was done for ages. In theory because the soap was in a powder from it dissolved faster in water and mixed easier than the other packaged soap for wash day, chips or flakes (Chipso or Lux Flakes).