Not exactly, the reason people think you need to get low and forward is a side effect of traditional stems and modern geo. With a long and low cockpit with a low and forward stem, you can’t get that far back before you run out of arm bend to easily get the bike leaned over more than your body. You need to get low and forward so that you have enough bend in your arms for control when reaching down for your low and forward bars. This is accentuated with a traditionally oriented long stem. When you lean the bike over with the bars turned, your bars drop down to the inside of the corner even further than your frame. You should mainly drive your weight through your feet for loading the bike through a turn and use the bars to leverage the bike around underneath you while keeping steering control. Remember heavy feet and light hands. The RR stem brings your bars up and back to meet you instead of you getting low and forward to meet them. This allows you to keep all of your weight going through the bottom bracket more comfortably and easily. The rearward weight bias helps to overload the rear instead of the front, helping it to break loose first in a controlled slide, and helping the bike to oversteer. This is why you will see more riders burping rear tires than front tires when demolishing really fast tight corners; the rear is seeing a higher load. This is also part of why you want higher rear tire pressures.