It's useful to recognize it, while simply abiding by only the parts of it which suit you. After all, if you need to, you can always ignore it and deny it.
On the other hand, the Thirty Years War caused such destruction that the institutional memory in European nobility lasted 250 years. Total warfare on such scale was only seen again during the Peninsular War.
Absolutely, and I didn't mean my post to come across that way. This topic makes me a bit glum, and I think that comes across as defeatist, but I'd rather take on the correct, losing fight, than not fight at all.