Let me tell you about a coworker of mine... she was raised by neglectful parents in an impoverished household. She acted out to get attention as a child (still does, though she's toned down some), and was very irresponsibly parented. She had sex for the first time at age 13 because a 30-something-year-old pushed her into it. That would qualify legally as statutory rape, I'm pretty sure, had anyone in that situation actually been aware or cared. She continued having sex after that, seeking attention and affection she wasn't afforded at home. She dropped out of high school in her mid-teens and got pregnant shortly after, in response to which her parents threw her out of the house. Her mother has told her she isn't interested in seeing her (her daughter). She sometimes sleeps with an article of her mother's clothing at night because she misses her mom. Fortunately some people at work have helped take her under their wing and she's matured incredibly since she first started working.
But this girl is a child herself, and was never ready to be a parent. She got into having sex because an adult coerced her and she was never guided along a better path.
What you've said sounds reasonable in theory but it's like so much conservative ideology: it only works if you assume the person is starting off at 100% with all resources available to them. This girl was kicked down before she even got started. A mid-teen girl isn't old enough to be responsible for herself, much less a child, much less after her own parents have neglected and rejected her, much less after being raped.
The situation is about personal responsibility but people so often fail to take into account that life doesn't always treat everyone the same and many people are not well educated, not well raised, not guarded, not helped. A child can't teach themself how to be healthy and personally responsible, and if their parents and their community fails them in that, how can we hold them up and say to them that they alone are fully personally responsible for raising a child?