A ruling is for when the rule is unclear, like the jump rules. A house rule is for when the rule is clear, but you change it, like the gargoyle rule where there is no roll involved as they are automatically indistinguishable from statutes. There is no inconsistency or contradiction.
You say the rules aren't clear because you play it your way. There's room for uncertainty, and that means another DM could make a ruling that a roll is necessary. No house rule is needed.
Sure, if you ignore the intent of gargoyles for 5 editions and the wording that goes with them, you are able to come to that conclusion. I can ignore that a longsword does 1d8 damage and change that, too. The rules state flat out that they are able to be perfectly still for YEARS. That's simply not possible if they are rolling dex checks with a 9 dex whenever someone comes by. Feel free to ignore the wording and rules, though and make whatever rule you like for the situation.
Previous editions are not controlling of this one. Referring to them solely in the context you have is an appeal to that authority -- misplaced as it is. Your strawman of the longsword isn't indicative of anything -- yes, you could rule that, but longswords do a d8 in 5e (unless wielded two handed, of course). That doesn't aid that you're relying on how previous authority did it to say that current authority does it the same way -- absent that specific rule, though. It's an appeal to authority, Max.
Incorrect!!! I realize that house ruling it to the more appropriate disguise skill is worse. -2 being worse than -1. If you're going to ignore the rules and intent of gargoyles, though, you might as well do it in a more reasonable way. It's not like making the already super crappy house ruled ability worse is going to mean much.
Um, gargoyle INT and CHA are both -2. What is incorrect? And, the point is that the rules and intent of gargoyles is not being ignored when the DM uses the basic play paradigm of the system: yes, no, maybe; if maybe, roll. A reasonable DM could look at that ability and say that it's uncertain if the gargoyle remains motionless. This isn't a houserule, nor does it ignore rules as it relies on the core paradigm of the entire rule framework.
The game as for 3 editions now simply used averages to represent creatures in the monster manuals. That doesn't mean that they all have straight 10's. It's a convenience for the DM to know the averages for various creatures for when he doesn't need or want to roll for them. 4e went a step further and didn't even have you use stats unless you needed to, but like gargoyles the idea is the same.
Please cite the rule, Max. You can't, because it doesn't exist, which means you're relying on your preferences to set a 'standard' and saying others not following that standard are not following the rules. No, you can make a commoner stat block however you want -- you, as DM, are empowered to create NPCs for your game. But, that doesn't mean that 3d6 is the core assumption for commoners, and another DM choosing a different distribution is using exactly the same authority you are. They're just not telling others that they are wrong for doing so.
Context is your friend, dude. For several posts I've been referring to the various editions to show that gargoyles have been treated the same. I hadn't looked up 4e yet and just tossed it in there. I did not say that "4e does it this way, so it's right because 4e says it is." I simply added yet another edition to the mix of gargoyle examples.
The timing of your intent doesn't change the appeal to authority, Max.
Nope. Go read it a few more times until you understand it. Study up on context while you are at it.
I've got a great handle on it, I don't need to review it. When you claim another source is the guiding principle on a questionable issue, and further do so without engaging why the current issue is questionable, that's an appeal to authority. Make your case without referring to prior editions -- then we'll see if you have an argument that isn't an appeal to authority. Just use the 5e rules and the trait and tell me that it's unreasonable to determine that the gargoyle remaining motionless might be uncertain and need a roll. Don't tell me what a previous edition did, make
this case.