I've seen that too. Or when the framework chosen goes away. If the person at a small restaurant or non profit who understood the page goes away you can at least find someone to come up to speed. But sometimes it relies on stuff that just isn't there anymore and you have to start over. I'm not in web dev, or whatever its called, but is there some technology in the space that is the equivalent ofba T-shirt and blue jeans, or a charcoal suit, that will be fine for a couple decades with only informational updates?
You have to constantly install updates for it to stay secure, then every second update your theme breaks, you find out it's not updated for the new version and have to redesign the whole page.