I see people get held up by the instances all the time. Not sure what's complicated about it, since it works exactly like email, but everybody seems to want there to be a single instance. They don't want to choose, as if it matters at all.
It's not exactly the same as email though. Email servers don't have a culture and you don't generally interact with other users of your email server unless they have given you the email address. And most people don't choose their email server. For personal email they use Gmail/Yahoo/Outlook and at work they use the provider their IT Department chose.