The author is wrong that Google and Microsoft don't do this level of illustration - they do and have for a while. They just do it on their home search screens, not on their App Stores
Do you have some examples? I have not encountered either. I'm familiar with bing showcasing interesting photos, which is fun, but not at all comparable to an editorial team commissioning graphical illustration for their content.
Believe the parent is referring to the iconic and world famous Google Doodles.
The Android weather widget has an illustrated frog.