Yes that makes sense.
Indeed, the first time I created an online community to co-define an upcoming conference, the launch version of the website was published in February for a conference scheduled for October. So not exactly a quick process.
However, the resulting community was not really a tribe, either — it was simply too professionally-oriented for that (or perhaps it was because it was 2002?).
On the other hand, I’d hesitate to put it on the same level as Reddit or Twitter … although, come to think of it, we (DG Information Society of the EU Commission, or ‘INFSO’) did have “INFSO accounts” before Google had Google Accounts, so who knows what could have happened if they had really developed it? ;)
More details on this very old example, in case you’re interested (and prepared for a really bad, overlong slidecast):
Trans-European online Communities of Practice should become a key element in the European online community , but…mathew.blogactiv.eu
… and here’s something a little more recent, as I’ve just decided to see how the three communities set out during my EuroPCom conference workshop last year fit into your framework (your input most welcome, full context here):