Does conventional current impede qualitative understanding of any circuits?
There are several levels at which we can try to understand the behaviour of an electronic circuit.

There is circuit theory, with Ohm's Law, Thevenin etc., a flow of current, voltage drops etc.

There's physics, with electrons, atoms, movement of holes

There's physics, with Maxwell's equation, propagation of waves along wires to components

There's physics, with quantum theory, forces between electrons being mitigated by photons

You always use the one most suitable for the questions you're trying to answer. If you are doing circuit theory, with conventional current, that is quite capable of handling frequency response of filters, lighting of LEDs. Swap the sign of conventional current, and all your equations have the potential to move a minus sign from one side to the other, but all the conclusions remain identical.

If you want to design a new LED substrate, or a Hall sensor, then you need to worry about atomic physics and what electrons and holes are doing.