There are people who think engineering is basically Lego but bigger, and people who think engineering is applied physics.
They're different jobs.
The Lego level is more like being a technician. You can slap a few ready-made building blocks together, maybe tweak them a little using basic algebra, and you've got your design.
That's fine for guitar amps and simple synth circuits and such.
But if you use that approach while designing the control circuitry for a power plant or a rocket motor, in the best case failure will be very expensive, worst case people will die.
That's where the real engineering happens. You're modelling systems from first principles and you know enough to be fairly confident that the equations you create to characterise a complex design with multiple inputs and outputs accurately predict its behaviour.
If you start with hobby electronics you have zero experience or insight into that level. So when you begin your course you're completely blindsided by how much math there is, and have no idea what it's for.
And some domains, like robotics, have even more math. You can use plain old EE control theory, but you can extend it into modelling systems using Lie groups and Lie algebras - which are more often used in quantum physics.