There's a lot of misinformation in this post.

The Affordable Care Act basically eliminated all health plans that provide no coverage for preexisting conditions. All private plans are required to cover that now. ACA plans are private plans.

All health plans come with the option of covering just you, you and your spouse, or you and your whole family. It obviously costs more to cover your whole family, but it's way less than every person getting their own plan.

Most plans have a deductible - meaning your insurance doesn't "kick in" until you've paid a certain amount. But preventive care and an annual checkup is covered, and your insurance might get you good discounts on a lot of care. Also, you have a choice of paying less per month and having a higher deductible, or paying more per month with a lower deductible. This is exactly the same as auto insurance, home insurance, etc. - those all have a deductible too.

The ballpark $400/month is meaningless if you don't know the person's age, gender, and state at a minimum. A 25yo woman living in Idaho might pay $200/month, and a 60yo man living in New York might pay $1,800/month for the same coverage. It really does vary by that much.