I'll always be amazed at how Skype went from being top dog in 2010 to not even being considered a choice in 2020. How did Microsoft drop the ball so hard that when the Pandemic rolled around everyone decided to use the then-unheard of Zoom instead?
Taking a general public lens here. For vidya, Teamspeak/Mumble provided better quality & latency but Skype remained king for its ease of ad-hoc calls until Discord blew it out of the water.