Cisco WebEx and Jabber own corporate voice communication (mostly because everyone uses Cisco VoIP phones). Skype is used mostly in the SMB market.
But it didn't back then, and it's only called Skype because MS acquired Skype, not the other way around. At the time of the acquisition, comparing Skype to Office Communicator (as it was called before Lync) was a stretch at best.
Skype for Business is just rebranded Lync. AFAIK there aren't any new features that were integrated across from Skype. Hell, it's still lync.exe.
We just 'upgraded' from Lync to Skype for Business and as far as I can tell it's exactly the same program with slightly different UI chrome.