Yep, that’s totally true. Profiling & debugging tools are designed for sampling the behavior and performance, and not primarily for understanding architecture. Still, they’re great for inspecting call stacks, which can be pretty damn helpful for certain parts of understanding the code.
IMO there’s no real substitute for getting the design explained by the people who designed it. (Of course this isn’t always possible, but when it is, take advantage.) Automated tools can never prioritize the explanation nor summarize what parts are critical or tricky vs what parts are incidental or trivial, and they can’t tell you which parts should be redesigned because they were slapdash vs which parts look ugly to a newbie but have a long list of hard to see requirements, and touching things should be done with extreme care. Good diagrams are very helpful, but best used as a supplement to in-person stories, in my opinion.