Point of note, Teams wasn't built from scratch it was more like a remodel of skype which they already owned. If you start looking under the hood at various aspects of teams one will start to see Skype all over the place.
I don't know if they updated this yet, but one location this was evident was on Linux. During a Teams call, if you looked at the applications using pulseaudio, Teams would show up as Skype.
It looks a lot more like a remodeled Lync (eventually rebranded Skype for Business) than a remodeled Skype, basically Lync but written in Sharepoint, hence the up to 1 hour account creation and license syncing delays.
