But they have to actually defend it, with evidence, through peer-reviewed works. They can't just say "ain't it slightly suspicious that.... therefore advanced race of early humans is obvious".

Two sides, usually more, are constantly arguing one way or the other, and as time goes on there are shifts, sometimes definitive ones. That's academia in a nutshell. It's fluid, it's constantly changing, but it has strict baseline requirements for evidence.

One that is commonly used for undergrads is: tell me when and where the trireme was invented. The ancient sources don't seem to agree, and the one that really comes out swinging is written long after the others. The archaeological evidence is a bit clearer, but still hard to say as ships don't tend to preserve well in the long-run. So throughout the 19th and 20th centuries historians were looking all the evidence they had and arguing one way or the other, all with some fantastic points of view and interpretations -- academia ENCOURAGES this. This is what we do.

But you do need evidence to back up your interpretation.