The electron is NOT the only possible charge carrier...
In metal salt electrolytes for example the ion is the charge carrier, hence conventional current and charge carrier movement are in the same direction. Electro chemistry was a huge deal as an early user of electricity, think electroplating, also things like aluminium and sodium production, it is only fairly recently that power for electronics has exceeded power used for electro chemistry.
Now in a metal the electron is the charge carrier, but that is mostly a metallic conductor thing, in a semiconductor the picture gets WAY more complex.
Unless you are dealing with particle accelerators, electro chemistry or the gory details of semiconductor doping it really does not matter and the math works either way, very few engineers care about electrons particularly, leave that to the physics types.
Any decent physics book discusses charge on the electron, and any decent undergrad EE book mentions it then promptly ignores it outside of the chapter on device physics because it is not generally important to understanding the engineering as opposed to the physics.