Maybe this is where regional differences come out as most students in the UK have had some programming lessons before starting uniAt the level of professional-standard software architecture for UIs?
There have been some positive efforts in the UK over the past few years to introduce programming as a more serious subject at secondary school level (roughly, ages 11-18). I think it's great if kids get to write a simple mobile app to chat with their friends or make a simple game, instead of only learning things like how to use a word processor or graphics program. I think it's great if there are teachers in schools who themselves have the skills and knowledge to help the kids do that, too.
However, there are plenty of new starters entering the industry who have just graduated with degrees in CS or related subjects from good universities and still won't have been exposed to these kinds of ideas at more than a trivial level. I'd be surprised and impressed if I had a school-leaver turn up for an interview for a programming position with more than a passing knowledge of these subjects.
For what it's worth, I don't think the original author does themselves any favours by inflating their experience as they do. The way they describe themselves in the introduction on their web site seems rather out of proportion to their actual experience, and their CV screams "I read a guide to how to write impressive-sounding CVs and I'm trying way too hard". But as a card-carrying member of the "I thought I knew everything at the start of my career and tried way too hard" club, I think you just have to see that as a combination of genuine enthusiasm and understandable immaturity, and give them credit for having a go and sharing their experience. I'm happy to see someone at that stage in their development taking an interest and spending the time to experiment and discuss and learn, and surely we should all be encouraging the next generation of programmers along that path?