[rhn_mk1]

In practice, it doesn't matter what an "actual" extension looks like, but how your product is viewed by customers, because those are the ones you want to lock in. And judging by HN comments, to very many people, Git means Github, making it an extension, if not outright a synonym.

And their extending has nothing to do with open standards, which is worrying due to the potential to create lock-in.

[maccard]

By that logic, anyone who builds a product around an open standard is guilty of EEE. A web browser that implements a sync feature, an XML editor that implements syntax highlighting , an RSS reader that implements link previews all "embrace" open source standards and "extend" their core open standards with non-standard features, which is _exactly_ what github have done. They have been excellent players in the git ecosystem.

[rhn_mk1]

I think this conundrum can be broken up by noticing how pervasive one extension is. A feature that has become identical with the core product in the eyes of a layman is problematic in the same way as thinking "IE6" is the same as "the web". If there's no awreness of choice, then the only outcome is further lock-in.

Implementing "sync" on its own doesn't matter that much, because few people think "sync" is a defining feature of the web standards, or that preview is an inherent part of web feeds. The awareness of alternatives still exists (I hope).