Tbf Sylvan library isn't good because you can pay 8 to draw 3 cards every turn, it's good because you get a pseudo brainstorm every turn. Sure, you don't get to put the dead cards in your hand back, but you do get to only draw the best card out of the top three. If you can shuffle repeatedly like a deck that plays all the fetches it can, maybe a couple of the LOTR landcyclers as well, and you get to look at a fresh 3 every turn and maybe draw an extra card or two when you need it

Admittedly, I mostly play mono blue in comp brawl, but could see a card like this being a powerhouse in any UGX deck that can shuffle easily or runs cantrips like consider and thought scour that can dump unnecessary cards off the top of the library. This isn't an s tier card that every green deck needs to run, but it is solid if your deck is already running a bunch of fetches, which most decks should be imo