>>720702441
>Toby doesn't want you to worry that there might be a bunch of meta-routes that all individually begin with an entire True Pacifist run.
Flowey is cautioning you against resetting because it would undo all the work you did to get the "best ending" for everyone. There's absolutely no reason to assume it's actually about Toby putting up a coded stop sign so completionist don't do extra True Pacifist (despite the fact that there is in fact content you can only see on a repeat True Pacifist run).
>Because starting to think like that would make you waste a whole lot of time and Toby doesn't want to waste your time.
There are at least 8 major variations of neutral endings which mostly amount to changing Sans's monologue, and a ton of smaller things the game keeps track of which also slightly change the ending and affect things throughout the game. This amounts to roughly 100 different possible endings to Undertale. There are a shitload of different possibilities for completionists to explore even if a normal person would consider most of them a waste of time. What you're describing is not the philosophy Undertale was built around.