I am in favor of splitting the categories.

Having more categories gives people more options for fun ways to speedrun a game they love. Certain people will obviously prefer one category over the other, but the popularity between two categories will change over time as runners compete with each other when their times get close.

Imagine only having any% as a category, in any game. Once somebody gets a really good time and no new strats are found it will become a dead game.

New strats can also be found for different categories from playing other categories. The more ways to play the game there are, the more ways to run the game there are. It's a no-brainer.