Thanks for asking the question. I care about y'all.
The first time I saw this practice I was stunned. I had a hard time breathing. Thanks for bringing that memory back as a reminder.
Not me, not on my crew, not with anyone I hire, and it would be a point of issue to anyone around me doing this while I was on site or knew of it.
With all the variables we deal with in doing our work in three dimensions, I can't see any advantage.
How many times has Mr. Tree reached out and touched us in an inappropriate place? If it can happen, it will.
If its because the saw won't startup, tune it. If your arm gets tired, get a good handsaw and use it to increase your strength.
If its the time you save, look elsewhere.
How many survivors of incidents said to themselves, "Oh, just this once [more]." ?