I have two Dremel tools. One is a couple decades old and has "solid state speed control." The other is fairly new.
My old Dremel had much more constant speed under load, at any setting of the speed control. The newer one, if you set it at a low speed, it just stops when you apply the tool to the workpiece. I have confirmed this with more than one Dremel of the same model. To control the speed now requires a combination of setting the tool and then carefully maintaining constant cutter force.
Any guesses about what's different? The motor, or the electronics? It's as if Dremel lost a good design, and replaced it with something that doesn't work quite as well.