I cannot remember the chemical name of the concept of how detergents and soaps work, but basically, the detergent molecule has a dirt-loving end and a water-loving end. The detergent molecules attach to water, and then attaches to dirt when it comes into contact with it, lifting it out of the fabric and holding it in solution. If the right combination of temperature, time and agitation are achieved, nearly all soil is suspended in the wash water and removed in the first spin. Rinsing is there to remove detergent residue, not soil, and suds have nothing to do with the cleaning action underwater.
This is why they used to say not to agitate too long, because the "hydrophilic" end of the detergent molecule would loose its attraction to water and redeposit soil on the fabric. I haven't heard this argument used in a very long time. I guess we have evolved! (And with the 50 minute wash on my Miele, I'm glad this isn't a worry!)
With the overflow rinse, I bet that nearly all the fresh water entering the tub is pulled into agitator and doesn't escape out the top until it has made at least one rollover thru the load.
I too never had good luck with vinegar as a softener. I use it like Greg to cut alkali, especially if I use ammonia in the wash, but never noticed any reduced suds in the rinse, reduced linting or softer clothes coming out of the dryer (and with 7 cats, I would notice less hair).
I do use softener on my towels, but it is only about 1/4 the recommended amount. This cuts any residual suds and adds a hint of softness with just about no fragrance and no adverse absorbency effect.
I have noticed that the top 3 detergent makers (P&G, Lever and Colgate-Palmolive) have added anti-suds ingredients to all their liquids. I mop the floors at my laundries with detergent leftovers. If I start filling my mop bucket with water and a cheap detergent like Sun or Xtra, I get lots of suds, but if I add All, Gain, Tide or Fab, the suds disappear. Filling the bucket with a top-shelf detergent, the suds disappear very quickly on their own.