For me it was the reverse. I was a random highlighter since I was a kid on Windows machines, but after I bought my first Mac the behavior just kind of stopped.

I also had another habit I dropped, in part because Mac OS X never supported it, but on Windows I would middle click in the middle of the screen and position the cursor just under the, well, scroll anchor I guess I could call it, leaving the page to auto scroll at a comfortable speed while I took my hands off the mouse and just read. If I recall correctly, if I did it just right, then the page would not just auto scroll, but highlight everything along the way.