Give the comments in this question Will Kerbal Space Program 2 have Lagrange points, halo orbits, and other 3-body goodies?, I wander what questions related to KSP are on topic.
I propose the following being on topic (everything that has a counterpart in real life space exploration):
- comparison of orbital mechanics with real life
- comparison of rocket parts with real life
- all stuff not implemented in KSP (ignition systems, life support, ...)
and the following off topic (all stuff that is not related to real life space exploration):
- bug that must be reported to KSP's developers
- new features in the game (or other roadmap related issues)
I argue the linked question could falls into "new feature added to KSP" and "comparison with real life orbital mechanism" but I fail to see how answer can provide insight about the second topic.
EDIT: Another question (What are the best settings to make KSP more realistic on ps4?) illustrate a case I didn't think about.