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.
It's why we always need competition in all areas, when you are the market leader, you stagnate. Once something better comes around, it's already too late.