The US isn't any more concerned about sexual orientation now than any point in the past. Back in colonial times, it wouldn't have been safe to be anything other than straight with all the hyper religious colonists. They were even forcing their gender conformity and the straight sexual orientation on the Native Americans. Baron Friedrich von Steuben got a pass for being gay, probably because he was the one in charge of training the troops for Washington. 100 years ago, you could be killed on the street for being anything other than straight or denied jobs. The Lavender scare of the mid century brought this more to light. The AIDS crisis that started in the 80s and bled through into the 90s and 2000s as new medicines were being invented, further brought negative light to sexual orientations outside of straight. The cause of all of this attention to sexual orientation has been the religions brought over by colonists.
In recent years, sexual orientations outside of straight are finally being seen in a positive light with Lawrence v TX (2003) legalizing same-sex relationships and Hodges v Obergefell (2015) legalizing same-sex marriages. In Bostock v Clayton County (2020) legal protections against job discrimination based on sexual orientation and gender identity were finally put into place over 70 years after the start of the Lavender Scare.
The attention to sexual orientation has always been part of North American history. It has just changed from acceptance with the Native American peoples to hate, death, and intolerance under the colonists, to a more accepting present day. With some of the positive news in recent years, it can be easy to forget (if you're surrounded by progressives in a blue state) that the hate of sexuality injected into North America in the 15th Century still has hold over large portions of the population today.