Code that isn't executed and doesn't have anyone to care for it will often 'rot' inside of a larger codebase in my experience. When that happens, it adds mental overhead whenever anything related is refactored or changed, and can sometimes do nothing but create barriers for further improvements.

In this case, it looks like it was a number of unused architectures that were being put to pasture - anyone who is interested can look through commit history and pull back what they need if they're invested enough.