Since the early '80s at least, urethane suspension components were touted for racing and spirited street use for just about every kind of car. Sway bar bushings, end links, strut bushings, control arm bushings—basically everything rubber on a suspension should be replaced with urethane to stiffen up the chassis for competition, according to all the experts at Car Craft Magazine, etc.
These days I'm not even sure this was ever true. Maybe if I was racing I'd learn for sure, but for driving on public roads with street tires over any distance...maybe the stock engineers knew something Car Craft (and its advertisers) didn't.
At any rate, the urethane-everywhere-edict doesn't hold in the air-cooled VW world because those urethane parts are (usually) made as cheaply as possible. I don't know if Impala's friend is exactly right on the details, but I know from experience that @ALB speaks the truth on this matter.