I agree with you, however all boats eventually will have no economic value. If you buy a boat/sailboat and think you have a investment think again. Forget the original cost, just add in the dockage, electronic upgrades, insurance, maintenance, registration, and the list goes on.This is 100% correct, re keels and condition.
Years ago I actually though about making an offer on a 28. I liked the boat. Fast forward to 2019, and many of them will be close to having zero economic value (net value after you subtract cost to remedy flaws).