Offering a child a small treat (whatever it may be) might seem unobjectionable, because parent/carer and child both ‘win’. But what’s really happening here is that you’re implicitly teaching them that if they want something that seems appealing, to get it they will have to do things they don’t want to do. You’re essentially supporting a pattern of exchanging one’s happiness/dignity/ethical standards/morals for some prize.
When you struggle against or take a coercive approach with another person, the natural response of that person is to defend their corner and fight back. The same happens inside our own minds. When you are fighting a part of your own mind, that causes the part you are trying to stamp out to dig in, to entrench itself, to defend its corner more vigorously.
If your young children are curious explorers who like taking things apart, find more things for them to take apart. Embrace their interest.