It is an act of cultural revolution. The Weather Underground too wanted to Smash Monogamy (they engaged in partner swapping/swinging even with members of the same sex and it was wrong to say no to someone).
Free love isn’t free. It’s about smashing the institution of marriage and fidelity.
Maybe it is considered an opiate of the masses (have them distracted always searching for a hookup).
Planned Parenthood is a sex positive proponent. They claim that abstinence ‘doesn’t work’ but dig deeper and you’ll find that they abhor abstinence because it is counter to their worldview. It’s ‘unhealthy’ because it is a denial of sexual desire. On a corporate level, they oppose it because it is bad for business (gotta keep ‘accidents’ happening to keep the money rolling in).
It isn’t about ‘family planning’. Margaret Sanger is on youtube (Pathe News, 1947, UK) demanding ‘no more babies’ for 10 years in Western Europe (no ‘choice’ in the matter, if you can’t have them after the 10 year ban is up, then it sucks being you).
So they want to divorce the sex act from the procreative act. This too smashes the concept of ‘family’ (married or not).
FWIW, I think the sex act has already been comprehensively divorced (nice choice of words, BTW) from procreation.
Most people today think of pregnancy not as the natural and normal consequence of sexuality, but as an accident or even a disease.
Of course, there is no possibility of pregnancy with a great many of the sexual activities they are most anxious to promote.