- It's a bad user-experience as players can end up playing a game without the mods they enabled. This causes problems when a mod opt depends on another mod with unfulfilled dependencies, see Optional dependencies being overridden/turned into hard dependencies #8601
- It results in a complicated mod dependency algorithm
There is a warning that this will happen in 5.6.0.
To make things easier, 5.6.0 will have dependency error information in the Select Mods dialog:
For more info: https://github.com/minetest/minetest/issues/12217