to get it started into wood or anything else.

Along came Phillips and solved that issue. I would assume it sticks around due to ease of manufacture and its universality.

One of the things people like about it is also its downfall: not always needing the exact size driver for the screw. People are forced into using the correct size Torx drivers as an oversized one won't fit and an undersized one will only spin. But with Phillips they can often get away with using an ill-fitting driver...until it strips the head. And then they curse it when reality is the issue was using the wrong size driver.