This is a ridiculous distinction. Both examples are highly idiomatic language, with no fixed definition that's even remotely close to what you claim. The original statement was perfectly understandable, and it's obnoxious behavior for you to try to pass your preference off as a "correction".

I don't understand the distinction. If anything is now gone and wasn't destroyed in an unpreventable disaster or purposefully, it was "poorly maintained." Doesn't matter if it is 100 years old or 10,000 years old.

Well, there is no reason to maintain most of these structures. They were mining cabins, but the gold mines were closed up long ago. The “time” when these structures were needed has passed, so they are not maintained and are rapidly returning to nature. Soon all that will be left to mark them will be some square iron nails.

It's incredibly easy for an all-wood structure built in 1920 to be completely gone in a hundred years, especially in a harsh climate.

Sure there may be wreckage of it, but it's lost to time.