That was my reaction to the Fighting Fantasy books article. The wikipedia article on 'Gamebooks' gives a better account of their history.

Incidentally, I have one of the early Tunnels & Trolls solo books for sale in my shop: http://www.shopontheborderlands.co.uk/product/beyond-silvered-pane-looking-glass-dungeon-softback-solo-adventure-tunnels-trolls/