Oscillators are supposed to oscillate but when you want them to, they don’t resulting in debugging.
Amplifiers can have a big phase shift and gain which fulfills barkhausen criteria which is the fundamental requirement for something to oscillate. Oscillating amplifiers are usually a very bad problem because it trashes the signal you are amplifying and tends to suck up a lot of power.
Fuses take a glacial amount of time to blow compared to an integrated circuit. When something goes wrong the IC blows up way before the fuse goes.
Indeed. Also, the purpose of expensive integrated circuits is to protect the delicate fuses in your design.