Quote: "... but I have come across everyday use cases of data structures and algorithms when working at Skype/Microsoft, Skyscanner and Uber" Considering Skype

Quote: "... but I have come across everyday use cases of data structures and algorithms when working at Skype/Microsoft, Skyscanner and Uber" Considering Skype is at best laughable compared to other IM applications, I'd not boast about working on it. I used Skype over 10 years and after it got bought by Microsoft it gradually started to be worse and worse, to the point I had to look at other IM in order to communicate with my clients. I have a question, why is that Whatsapp and FB messenger can and will deliver notifications when you receive a message every single time, while for Skype this seems to be an unachievable feature?