duh

No surprises here :-p

Sex is a concept for people who are not singularly whole. People who do not get enough from just themselves. People who don't feel complete until they're with someone else, even if it's superficially.

I'm not one of these people. So I do not need sex.

Well, to be fair, it is also how we as a species propagate ourselves. ;)

It can also simply be something fun and pleasurable, a way to relieve stress, emotionally bond, and just enjoy one's self.

Everything in your second sentence goes back exactly to what I was saying. People immerse themselves in it out of a lack of completeness. If you were complete you wouldn't need such superficial happiness or emotional connection. 

Humans are social animals, there's a reason why we have such an advanced language.

Or maybe people just like to engage in pleasurable activities, because it's fun and nice? Not just sex but also things like video games, movies, sports, or music. If "completeness" means not wanting to do fun things, that sounds like an awfully boring way to live.

Of course, because most people aren't complete. Once you are, you don't need such things. You become content with singularity

Not really. We live an a system that requires communication with others, so completely avoiding others is impossible.

The same way the local bar doesn't tell you to "gtfo" for crying about your dead dog from when you were 7, no one's subverting your safe space with "kiddie sex talk" snowflake.  It's people sharing personal experinces.