I apologize if I came off as passive aggressive, I was trying to advocate for what I think would be best for long term integrity of the leaderboards here. I will try to better explain what I should have stated more clearly in the first place.
While this community may be small now, it could be bigger later. I think it makes sense to set strict rules that might seem unecessarily burdensome now. If the game rose in popularity, it would be awkward to have grandfathered scores.
I'm not going to debate the magnitude of the impact of the grain, but having it more often makes the game objectively harder. Even when playing for time, your stroke count matters. My belief is that difficulty needs to be taken into account when first vs second can be a matter of milliseconds. Compounding this known difference in difficulty with the fact that difficulty level may yield other changes we don't yet fully understand, I think it is prudent to set a strict standard.
I'm not advocating for diluting the leaderboards with many categories, but setting a standard that can be used for fairly ranking scores and making it easy to compete across platforms. I know that, personally, I would look down upon a place that treated objectively different difficulty levels as the same. If it were up to me, I would set MVS Level 4 as the standard as that was what was balanced for arcades. If you are only interested in pure speed, Level 1 makes more sense, but that could lead to less challenging, lower variance, and more boring gameplay. Either way, I don't think it is wise to leave it unregulated when there are known differences.
Difficulty has an impact and does matter. I am certain it affects how many greens have grain. I'm not as certain about the impacts on wind. While I can't say whether or not it effects the average wind, I do think it has an effect on some kind of RNG seed. (this could matter greatly if a certain hole usually has specific wind on a set difficulty)
I think it would be foolish to treat all times/scores the same, regardless of difficulty.