Being curious, I looked at some of the other bits on the site. There is actually one promoting abstinence.
Planned Parenthood is among those pusing the Sex Positive Agenda.
Sex positive proponents oppose abstinence NOT because “it doesn’t work” but because they find it to be an unhealthy supression of sexual desires.
Planned Parenthood also probably looks at their bottom line. There is money in selling birth control and abortions but no money in someone just saying “No”.