Whatever, it paid the bills nicely for almost 20 years.
In fact popular IDEs / editors back then supported CVS, then SVN and pretty much nothing else.
You'd be amazed (or not) how little technical superiority matters. Developers just want to click stuff and get back to developing.
Which is not to denigrate git, which I love so much it hurts.
And for things like this:
>I didn't want to do anything that even smelled of BK. Of course, part of my reason for that is that I didn't feel comfortable with a delta model at all (I wouldn't know where to start, and I hate how they always end up having different rules for "delta"ble and "non-delta"ble objects). [1]
[1] http://lkml.iu.edu/hypermail/linux/kernel/0504.3/1588.html