Understandable choice, given that Skype is pretty much redundant with Teams. Back in 2004-2005 Skype was really hyped because of free voice calls through the Internet, but few days later several other messaging apps incorporated that feature; Skype’s thunder was stolen. Also its inconsistent branding was a problem: there was Skype for Business that later became Lync, ultimately becoming Teams. Skype kind of became forgotten and obsolete.
Skype was a beast at tunnelling through proxy blocking then acting as a proxy itself for other Skype endpoints that were not as successful.