My understanding is that the OG game began to collapse on itself between the story, the changes in the characters as the game progressed and too many unfixable bugs and that it became so bad that the only thing he could do was start over.
I also laughed too at that line in the game but it was more of a tongue and cheek jab at himself for the way the OG game ended up becoming due to lack of planning which BoN does seem to have done a better job at.
Also v0.83.5 is completely playable and fine as long as you go from 0.82 to 0.83.5 and did not play 0.83a and especially if ya follow my Strategy Guide (listed in OP as just guide) then you won't run into any major issues.
As for why I made my Strategy Guide is I do see him completing this game but also to help others get the most of the game. This includes seeing all the content as it took me playing the game 3 times besides digging in the game code and also talking with others who have also played both games multiple times as there is a lot of semi-hidden content to look for. But also I saw many complaining about the game being buggy when in fact they were jumping around in this game when it is a semi-linear game and if you jump around too much then you will miss certain things for example you need to start doing the hospital job asap before you do Morgan's Quest which you need to do before try to help Rosy or that if you don't complete all the schoolmates/School Quests before the Mafia Choice then you won't be able to complete them all when you go to the New House. I include many tips and notes in my guide for these and many other things too.
And since it is now BoN approved, even better.