Yes, development was being done in SVN but it was a huge pain. Continuous communication was required with the server (history lookups took ages, changing a file required a checkout, etc.) and that was just horribly inefficient for distributed teams. Even within Europe, much more so when cross-continent.
A DVCS was definitely required. And I would say git won out due to Linus inventing and then backing it, not because of a platform that would serve it.
I am not sure, it seems I did misremember. Though it's possible I was actually working with needs-lock files. I can definitely see a certain coworker from that time to put this on all files :/
And even in P4, you could checkout files only at the end, kind of like `git add`. Though this could provide some annoyance if someone had locked the file in the upstream.
A DVCS was definitely required. And I would say git won out due to Linus inventing and then backing it, not because of a platform that would serve it.