Yeah, the fireplace is the biggest hindrance of that. You can get that white page no problem. Or, if you really just love Sirrus or Achenar, adding the red or blue page from the fireplace (even if that's the only page) will free the brother.
If you notice, none of the other Mysts allow you to finish from the start. Riven... well... it's Riven (you need the journal, which means you need to go to Moiety, which means you need to know Jungle Island, which means you need to go to Book Island and Survey Island, and then you need to trap Ghen and free Cathrine... etc). Exile, you have to finish all the ages to get to Narayan. In Myst IV, if you know what to do with the Quetzy, you only need to finish Spire so you can get to Serenia... and Myst V requires you to finish all the ages (same with Uru).
I've played all of them except Uru and Uru Live. The musical score is some of the best there is... which is why I occasionally come back for more.
I'm on my way to finishing Path of the Shell... then I'll have beaten them all (save RealMYST... but does that really count?). I must also say that I have all the soundtracks downloaded. I think Myst IV tops my list for best soundtrack... even though the Gallery Theme of Uru is quite nice.