Why there isn't a booneless category?

Boonless does not exist as an official speedrunning category, because there are a fair few things in the game that can kill the run on the spot.

1. Hermes in particular is notorious for having many boons that are difficult not to activate (his dodge chance boons, bonus dashes, hyper sprint, faster attacks / specials, faster movement speed).
2. The 8 regular gods also have several boons that would probably kill a run immediately if one were to be forced to pick them up: attack/special/dash on nearly every aspect (since the optimal attack rotation for the aspects usually uses a bit of everything), vengeance boons (one is usually bound to get hit eventually when trying to speedrun).
3. Chaos is banned in boonless, meaning that one can not easily avoid situations in which one is forced into minibosses or other boon major rewards. because of all of this, the whole thing would be less skill-based and more based on not getting screwed over by boon rng.

If you feel like the speedrunning page for hades would greatly benefit from an official "boonless" or "boon purger" leaderboard (category extension for example), then join the hades speedrunning discord server and make a post in the #h1-category-suggestions forum about it!