What @hilariousandco meant is that you can put your twitter link on the provided area for additional handles;

And not to create a thread asking for people to connect with you on X (twitter)
However, some of use also like to keep identity sacred and connecting X account might reveal true ID, the forum is pseudonymous. Privacy matters to some.
To be precise, you can't have Twitter link on your profile as there is no dedicated place for it. There is some obsolette things that you can have on your profile like ICQ, AIM, MS, YIM. But yeah, you can have it on Website space or in your signature.
It's everyone's choice whether they want reveal identity or not, but having Twitter account doesn't neccessarily means that you will reveal idenity. It might be business profile or your nickname.