The author is talking about two orthogonal problems.

1. "Thinkism": As described, over-engineering before writing code for a complex system and seeing where it takes you. Maybe decision by committee, or just overthinking. But its like one form of replacing on-the-ground adaptable, creative thinking, with a dumber process.

2. Which should be completely separate, it's saying that students are mad if they're forced to think for themselves. This is a complaint about underthinking and the tendency of inexperienced coders not to come up with a grand plan before writing a line of code.

So which one is the problem? I'd say the problem is not knowing when to over or under-think something.