markusin, you're talking like you either draw nothing at all or your entire deck when you suggest "just buy more THs."
Can you elaborate what you mean here?
often you are drawing that treasure the same turn that TH is trashed.
That only happens reliably when you are drawing your deck, but you only need a net handsize increase of one before playing your TH to trash your TH into a Gold, so you can very easily draw up to a handsize of 8 without having the cards necessary to draw more cards. I don't believe that using the word "often" is even a little justified here, especially since gaining that treasure occurs AFTER drawing the cards from TH.
You're only going to be reliably drawing your Gold the same turn you trash your TH if you either have a very thin deck or if each turn you're either drawing next to nothing or a ton of cards with no in-between.
I'll admit that calling it F-tier was probably an exaggeration, but it's definitely not an A-tier like its ranking suggests. I'm not saying that TH is NEVER good (every Kingdom card CAN be good, even Scout), but it is easily the worst Smithy variant IMO.