Meanwhile one of the core services for our product that my team is working on is modeled as a weighted DAG because it is, in fact, the correct way to solve the problem. If I didn't study them in college, I'd be completely lost.

To be honest, I think there's a lot of unnecessary complexity in codebases due to developers not being comfortable with more sophisticated data structures & algorithms. You end up with a lot of workarounds and leaky abstractions because there are developers who only have arrays and structs/objects in their toolbox. Good engineering requires picking the right tool for the job, which is much harder to do when you have few tools to work with.

That's my issue with the whole "I've never used this stuff in my career" argument. That may be, but it doesn't necessarily mean that's a good thing.