Love of froth by housewives/persons doing laundry
Isn't new, nor is Persil's response.
Back when true soaps were used for laundry yes, froth levels were an indication of performance. This is due to several reasons but mainly because soap can and does act as it's own water softener in water. That is soap binds to hard water minerals but the process but this is not very efficient nor economic hence water softeners/builders such as phosphates, washing soda, borax, etc....
When doing laundry with soap either via machine or hand one was supposed to watch for a certain level of froth as an indication enough product was being used and was not consumed by hard water minerals and dirt. This is especially true if the water was being reused for subsequent wash loads (twin tubs, wringers, by hand, etc..). If the suds level went down you either added more soap or better simply started with fresh.
When P&G first introduced Tide as a "heavy duty" laundry detergent sales were horrible. Women conditioned to using soap found the non-sudsing product wanted becasuse Tide as then formulated didn't make mountains of suds. P&G reformulated the product using high frothing surfactants and viola, Tide instantly became a sales hit. This set the pattern for not only the USA but elsewhere as automatic washing machines spread.
However the problem for Europe is that on that side of the pond as front loading washing machines became the standard, high froth detergents had to go. Too much suds causes all sorts of problems in H-Axix washing machines (as it does in top loading but few want to hear), so Henkel, P&G, Lever Bros./UniLever et al all had to come up with detergent formulas that used low frothing surfactants and or chemicals to control foam.
Dash, All, and a few other products were the first low/controlled suds detergents and were aimed mainly at those owning front loading washing machines. That market was never very large in the USA, and even though it could be used in top loaders many housewives still equated foam with cleaning power and so...