Andy (Lakeside on here) used to say that, that more oil meant a leaner air/fuel mixture. A retired engineer who became a licensed Stihl tech, main guru on this site fifteen years ago. I believed him, though some people said that was just what Stihl said to promote 50:1 for smog purposes. I recall once I shared that bit of info on another oil thread here, and some guy took offense, to the point of suggesting (via abbreviation, of course) that he wanted me to perform a vulgar procedure upon a certain part of his person. Poor fellow. I suggested he might have better luck with that on a different kind of forum. Yeesh.
I believe that the new 50:1 is so good it can be used in 32:1 machines. What I do not understand is why Stihl would make a premium synthetic oil that is not top notch in lube and detergency. It's Stihl, for gosh sakes. I really don't get that.