On the other hand, internal tooling like cider, bazel, etc. are so advanced at these companies that the old frameworks like vanilla javascript are a lot better

On the other hand, internal tooling like cider, bazel, etc. are so advanced at these companies that the old frameworks like vanilla javascript are a lot better than what outsiders using javascript have. Moving to Typescript is still a huge benefit but I don't think the old development was that bad either.