Henry is a member of a particular wiki community. He checks the recent changes of his wiki practically as if he checked his mailbox. He knows most of the other users of that wiki very well, and he contributes little bits and pieces, or at least corrects the already written things practically every day.
He knows the markup of his wiki by heart, and he also has very strong habits of when to use particular markup and how to organise the pages. He also knows the layout and mechanisms of his wiki well, and though it has its quirks, he's so used to it that it's the best and most comfortable interface to him.
He finds users that are new or come from other wikis a little clumsy, and he finds their use of markup rules, formatting of their text -- even the style and places where they put their contributions -- alien. He often corrects them to make his wiki more consistent. He believes in the openness of wikis, so he doesn't mind it -- although he sometimes wishes that others were less stupid.
He occassionally approaches other wikis, but they seem jarring to him. All the links are in wrong places, the page organisation seems wrong, there are some unfamiliar and strange rules as to where to put comments and when to refactor pages. Most of his favorite markup doesn't work, and in the rare occassions where he manages to get something right, it gets "corrected" by other users into some different markup.
Hence, he usually doesn't edit other wikis apart from some comments here or there, a corrected typo, a spam revert or a link to a page on his wiki.