Coworker has been working as a web developer at our company for 10 years... Yesterday I see him watching this video intently: https://youtu.be/PLA2FaOXkkg ?

Why surprised? There's always room to learn more..

Quite a few web designers are great coders and designers, but can't draw or make graphics.

I suck in Photoshop too, we are Devs not Graphic Designers :)

Hey, I don't expect everyone to understand paths and masking in Photoshop. But, if you have been working on the web for a decade you should understand how to do simple things like crop, resize, and save an image in web format!