There are reasons that a gentleman is esteemed more than just any normal adult.
Of course we are all adults, and people can do what they want. And if they have no regard for how their language makes others feel, then fine.
As for me, I know this… I swear entirely more than I should, and I’m not going to use the “we are all adults” excuse to try to justify my behavior, especially when I do my best in other aspects of my life to be gentleman-like.
But hey, you can if you want. It’s your life.