nowadays failure to reproduce is glorified

> Males back then didn't fail to reproduce from the same social situations as today.

Yes, but they could fail to reproduce due to other situations. I think from this

> Failure to reproduce basically means killed, exiled, or having your groups women taken (by force)

Only "killed" supports the thesis that males were slaughtered

There were other reasons. Early farming communities were almost always patriarchies where the sons stayed on the farm but the daughters switched communities. So local disasters that wiped out a single community took out a male lineage but not a female one.