I mean that’s fair but on the other hand, at best he is ignoring all the other threats out there. The Avengers are, as of Civil War, the only people on Earth who could have stopped the alien invasion.
Yeah. But, why did that invasion happen? Because Loki... wants power. So, again, Zemo is not wrong.
So, I seem to be arguing for Zemo. The thing is that, in a major way, he is right - all he is really arguing is that power corrupts, and if that isn't a strict truism, it is true enough of the time in our normal daily lives to cause great misery to humankind. So, finding a flaw in his argument in that regard is going to fail.
The flaws in his position are rather practical.
1) Power happens. In the MCU, human (and non-human) technology and understanding have power as natural byproducts. Unless he forces Earth back into the Stone Age, it is something that has to be managed, because it cannot be eradicated.
2) Power exists. Asgardians. Titans. Skrull. Kree. Eternals. Inhumans. The MCU galaxy/universe is filled with people who are naturally more powerful than humans. Unless he wants humans to be eternally victims of those others, humans have to harness power - and that means letting people have it.
These facts make his desire to eradicate supers quixotic and unwise. Superpowers and their application need to be managed, just like everything else in human existence.