StackExchange in general does not encourage personal interaction between members. SE is not a social network, and one of the reasons it manages to be so effective at topical QnA is it side-steps many of the complicating human factors.
They are not strictly opposed to it, they just go out of their way to make sure it happens off the network and not on it. Users do have profile spaces where they can choose to give up personal contact details or not as they see fit. My profile links to personal contact info, but many high-reputation users choose not to be contactable outside SE.
That said, if some discussion thread or comment was what got your interest, you can get the attention of that users by at-replying to them. If you comment on a users post or question (or if in a set of comments that they have participated in) with @username that user will be notified via the global inbox system. You could easily make a suggestion to chat in an existing room or have them contact you off network.