NO it absolutely is not planned anything but tamperproofing.
Take people like Ernest and I. Our non-adjustable carb stops working. What do we do? We buy a new carb. The stores make money. And, no doubt, when some peoples carbs stop working they get a new engine. Vs a Honda, for instance, or an older carb, you reach down and turn that little screw. If I was riding along on a go-kart with an adjustable carb, and I started adjusting it, all that will happen is I will make it run worse. (If it was running well to start with.) If I want to raise the rpm's, I will go to the governor. Once I have bypassed that and have the engine screaming as high as it will go, then maybe I can adjust it higher using the needle.
BTW, I am not arguing!
I am engaging in good-natured (on my part), friendly (on my part), debate.
I hope this finds you well!