It is unclear to me when someone needs to provide playtesting for homebrew suggestions and when they don't.
As an example, in this answer, MattDM provides a really good answer for the first half, suggests in-book tools for making adjustment, but then at the end makes a homebrew suggestion that wasn't tested by them.
In fact, they specifically state (emphasis mine)
So, another approach would be to beef up that feature — perhaps make the save DC just "damage taken" rather than "5 + damage taken". But this is a less predictable than the raw HP approach, so I don't suggest it without some playtesting and tweaking.
In this case, they called themselves out that their idea is untested and likely needs work. This alone seems to imply it needs testing and would fall under our bad subjective policy for suggesting untested homebrew and is idea generation.
But I also could easily be too critical of a good answer and I'm trying to understand where we draw the line. By understanding when we require more, it will help in evaluating future answers and build a stronger repository of useful information for stackizens.