"People shouldn't post about how the contraceptive pill can be prescribed for non-contraceptive reasons because it's sex negative" feels like a take that can only come from people who don't realise just how young some people end up being prescribed the pill
Like, fine, you, person in your twenties, might be comfortable being like "this is the pill I take to fuck without getting pregnant", but I don't think it's sex negative for a thirteen-year-old who has been prescribed it for debilitating period pain to not want to have to hide their medication from their classmates on an overnight school trip because their classmates think that the only reason anyone would take it is that they're sexually active
Also, maybe more importantly than social perceptions, many people who are 13-18 may not have access to people who will let them know that you can use estrogen and progestin / progestin pills or hormonal IUDS to stop/lighten periods.
The number of young people menstruating right now who don't know that there is a viable option to not be menstruating is staggering. There's an option to Just Not Deal With That and many young people haven't been told about it or been offered that chance.
So for those young people, yes, birth control can lighten or stop periods. The birth control pill can do this, IUDs can do this, implants can do this and injections can do this. Birth control pills you take every day, injections you get usually every 3 months, and IUDs/implants require a doctor to insert an IUD into your vaginal canal or an implant into your arm. Not everyone has their period stopped, but a lot of people do and of those that don't have it stopped they usually have it lightened. Talk to a doctor about what's right for you. Planned parenthood is super helpful for accessing birth control if you have one nearby, if not, most doctors should prescribe birth control on request barring major health concerns.
Throwing out there that IUD insertion has a reputation for being extremely painful but the New York Times ran an article just this week about actual pain management options you can and should raise with your doctor before the procedure if they’re too lazy to offer the information themselves.