It's because we live in a society in which children are an oppressed, marginalized, unrepresented group of people not worthy of basic rights. (Please don't read that as a pro-life statement.) We literally have about 6 million humans who are barely considered people, in the US alone. They are property, non human beings.
And of course this is linked to patriarchy, white supremacy, ableism, and capitalism. If you can't talk, you're neither valuable nor human. If you can't walk, you're neither valuable nor human. If you can't produce, you're neither valuable nor human.
The impact on Black, Brown, immigrant, undocumented, and poor children is exponentially greater.
Babies, toddlers and all human beings have the full range of human emotion. Because they are all human beings. Deserving of human rights, including the right to to develop healthy brains and nervous systems.
Infant and early childhood mental health is the developing capacity of the infant/young child to form close and secure relationships; experience, manage, and express a full range of emotions; and explore the environment and learn — all in the context of family, community, and culture.
Learn more about IECMH: https://bit.ly/3BaYnr6