It's quite a leap to go from your personal anecdotal experience to assuming that the data of hundreds of millions of people must be the same as your experience and was just ignored.
"If the Whatsapp team actually tracked the rate of user engagement with these Desktop/Web editions & compared this to the Smartphone/Tablet apps. They would agree with you."
Surely you are talking about them tracking the rate of user engagement across their userbase, not just the data of you alone?