Do you think the product manager of the first instant messaging tool considered that end users will share long texts using the product? Or that they will only send short text messages containing a few words?
Writing long texts instead of short messages makes the instant part almost irrelevant.
Same goes for sending endless emails instead of arranging a video conference call to clarify the topic.
It looks like the software products which have a large set of features available allow users to perform activities which make irrelevant the initial product purpose. On the contrary, a clear set of features keep applications relevant over time.
So, the next time you design a product think more about how it will be used, not by you, but by your end users.
And, at the same time, regularly evaluate how the features implemented contribute to staying relevant over the years.