I'm not sure I follow. Bittorrent is absolutely NOT a "serious" application from an enterprise perspective. Most companies don't use torrents and actively block the protocol (since the most common usages are unsavoury or related to entertainment, not business).
Whereas IMs are an accepted part of business processes (i.e. "serious").
> Whereas IMs are an accepted part of business processes
There was a very long period when IMs were not acceptable and actively blocked, especially at financial institutions that have a legal obligation to log and retain all internal communication for X years. I saw this at many different firms for many years.
That changed. perhaps torrent will, too. Nah, probably not :)
Everything can be blocked if you're willing to block everything else. Blocking something while leaving other services unaffected isn't trivial, and gets harder the smaller the data is. eg. if you want to block some bad guy from exfiltrating a 256 bit key, it's almost impossible to do because there are a million ways to do smuggle it out with stenography.
Whereas IMs are an accepted part of business processes (i.e. "serious").