The sloping top tubes do not REQUIRE any changes in the rider's position. Cut a photo of a rider from the 1960's out of a cycling magazine. Draw a line from the bottom of the stem to a point on the seat tube that is six inches below the seat bolt. You now have a bike with a sloping top tube, yet nothing else, including the rider's position has changed.

But, if the bike does NOT fit the rider...well...twenty years ago, some racing frames were offered in six to eight sizes. Today, some companies offer as few as three sizes. The sloping top tube allows them to claim that a "medium" fits half the adult males in the world, by adjusting the seatpost height, stem height, and stem length.

Twenty years ago, men's dress shoes were made in America, and could be purchased in six different widths. Today, most stores are selling Chinese-made dress shoes, that come in your choice of "medium" or in "medium", just like a communist-made bike frame. If buyers are dumb enough to think that "one size fits all", well, the vendors are happy to oblige.