Clearly, a damaged card is soiled in the eyes of most people, unless it holds some sort of memory to it, in which case its more personally valuable than anything else
Vivi Ornitier Little Vivi from Final Fantasy 9 doesnt necessarily look highly powerful at first glance, but the ability to grow, and to produce mana make him a powerful little dude
There are other resources you have to use to gain the advantage and good players will be able to abuse that resource usage
With minimal mana costs on these sorts of abilities, theres no need to tap yourself out every time you act, or to give new information away to opponents
Instead, you have to type "MTG" and then a random word (like "bracelet" or "clock) into Google or eBay and see what (if anything) pops up, often while digging through a ton of listings for Unwinding Clock and Illusionist's Bracers
For example, if you own an entire base set that youre looking to sell (or display), getting each card graded may be worth it even if an individual card is worth less than $20 as having the entire set graded would enhance its overall value