“UCI-legal” is not the same as “good for you”
Race rules constrain where parts can go. They say nothing about your comfort, health, or accessibility.
Governing-body rules (like the UCI's constraints on saddle position and bar dimensions) exist to keep competition fair and, in places, safe. They are a regulatory boundary for racers.
They are not a fitting recommendation. A position that's perfectly legal can still hurt you, and a position that suits your body might not be legal for sanctioned racing.
If you race, use UCI mode to check legality — but treat it as a separate question from 'what fits me best'.