Why can't we just leave it up to kōhanga and kura kaupapa?

The home plays the most vital role in terms of a child's language development. This is where intergenerational transmission occurs and where language use is normalised. Kura and kōhanga although equipped for teaching children te reo Māori, rarely produce high quality speakers of te reo when there is no home support for this. You need to take charge of your child's language development and support it from the home level.