The end of strategy guides was Final Fantasy X. Most of it was filled with “Go to this web address to see the solution!”. And the game even has the website featured on the title screen with as much space as the game title.
I don’t recall that, although you’re more or less correct on timeline. FFX-2 I used a strategy guide, no website links and the damn thing was practically mandatory. I’m glad there’s better guides from fans, now.
I have my Final Fantasy X still, even used it when I played the remastered version recently. It didn’t ask me to use the website for anything. I thought it was the Final Fantasy IX guide that required you to use PlayOnline for the actual solutions.