Map Enthusiasts

Racism, mostly.

Continents are a human convention, not an objective fact of reality.

The 7 continent model most English speakers learn is one convention.

Personally I prefer a 6 continent model that combines Europe and Asia into Eurasia.

Latin Americans use a 6 continent model that merges North and South America into "America". Personally I think this is silly because there's no rational basis to merge those and not merge Afro-Eurasia into one mega-continent.

Which you could do. A 4 continent model with Afro-Eurasia, America, Antarctica, and Oceania.

There are also completely distinct ways of deciding continents. The conventional ones above are mostly "large contiguous landmasses", with a bit of a cultural overlay.

You could do a much more heavily culturally-inspired take, which would make Arabia a distinct continent, and the Indian subcontinent, and probably separate Northern, Eastern, and Southern Africa into at least 3 continents.

Another completely different way of defining it is, of course, tectonic plates.

And the final one I'll mention is biogeographic realms which, among other things, moves the split between Oceania and Asia from the border between PNG and Indonesia to (probably—there are a few alternatives) the Wallace Line between Borneo and Sulawesi in Indonesia.

None of these is really more correct than the others in any objective sense. It's just human convention.