So what? React is one library in the ginormous pile of tiny little dependencies that come with any JS project that's large enough, and those don't have the same policy and are subject to the incessant churn of the ecosystem.

I've been using pretty much the exact same packages for a 5-year-old Django project with no need to migrate needlessly.

I've had to migrate JS apps that were just one year old and tiny, and the amount of pain was far larger than upgrading a 50k LOC Django project.