Just like all "principles" they shouldn't be blindly applied. Simply forcing SOLID upon a codebase won't magically make it better. In fact, I've seen codebases that "strictly follow SOLID principles" being terrible to understand, debug, follow, and optimise.
There will always be blind and zealous followers who will vehemently "protect" a codebase (or anything really) from impure modifications. They are the worst to deal with.