I feel like this can be argued so many ways. For instance, while code review might block some changes from being introduced into the system, it also does have more benefits than the "fluffy" ones you mentioned. Maybe an engineer that has more experience with the codebase can point out a way of doing something that is more in line with what the team's style is (earlier move toward standardized code vs letting people do what they want). Maybe you missed a utility function that already achieves what some of your code does. Maybe there's not a bug, but again a more experienced dev sees something that can be optimized and will save time in the future that would be spent on tracing system performance issues. The idea that we need to move ultra fast as devs... I think that is necessary in some cases, but I'm not convinced that taking some time to code review tasks is as expensive as you suggested. I mean even reviewing 1000 lines of code should take no more than 30 minutes. And if it looks entirely confusing and hard to follow, then maybe it's something to revisit because I guarantee you're gonna be spending longer if you have to go back and refactor/extend messy and unclean code that technically works. I think the key here is to catch things that stand out and not review the minutae.

This is just my opinion of the matter. On the topic of team building, I don't really care for all that stuff. Unit tests w/ CI and periodic refactoring are great for revisiting design decisions. Code reviews are great for catching bad design decisions early on, though so use it as a tool.