Right. Chesterton's fence isn't "never remove a fence". It's "understand why it's there before you remove it". If you look and find out it's for a long-unsupported platform, go for it.

In practice, a mature codebase is likely to have a mix of now-useless warts and seemingly useless but actually essential elements, along with some that fall in the middle (most often, in my experience: attempts to fix valid issues but in a way that no longer makes sense).