There's some truth to that, but there are many rules in a TRPG that aren't "guidelines" in any meaningful sense.
"A Medium longsword deals 1d8 damage," for example.
"A fireball allows a Reflex save for half damage," for another example.
My group has a strong preference for consistency in the rules. If it has been ruled in the past that oozes cannot be tripped, for example, we don't want the DM suddenly announcing: "Well, that's only a guideline. This encounter will be a lot more fun if you can trip oozes, so that's how it's going to work tonight." My group prefers that if oozes can't be tripped, then oozes can't be tripped; the rule is what it is, and that's that.
And where the issue hasn't come up before, my group appreciates having someone with vast knowledge of the rules and how they interact with each other, who can advise them against adopting interpretations that may lead to problems later.
I am, as ever, teasing above
but your game is short-circuiting the rules lawyering by arriving at a shared, and then consistent, interpretation. That's maybe quite a bit different to pointing at the rules and saying 'do it this way that suits me, eh, I mean the rules demand that we . . .'
Sounds like when your group meets something new you fit it into your game rather than reshaping your game to fit around the something new. This approach is, possibly, more consistent than rules lawyering which leaves a question mark hanging over the rule until the next time it comes round and the whole thing gets dredged up again. By negotiating your rules you probably get the best of consistency and player choice, so if you wanted variant oozes I'm thinking you'd introduce them and offer an explanation for them - maybe by discussion in advance, maybe by showing the PCs the lab where they were created first.
So, I like the guidelines label, because if everyone round the table agrees that a D8 is not a good measure of what a medium longsword delivers compared to other weapons, or you want to ratchet up damage across the whole weapons' system, an RPG says go ahead, make it 2D6 in your game.
I can add that I have an attitudinal problem here as a result of playing a deliberately experimental 'guidelines' game which encourages customisation and 'entertainment' mechanics.
E.g. the 'standard' weapons available to tribes/ races have grouped values, i.e. broadly similar weapons cause similar damage. Immediate 'wtf? isn't that a bit dull'. Not necessarily, there are plenty of variants available too, but there's a core set of similar weapons that helps new players to grasp the basics and focus on a system of bonuses, multipliers and other combat options. As a result, a new player is coaxed not towards 'do I use my D8 Longsword or my D8+2 Mace?', but towards 'can I use a backstab, do I have non-combat options, am I on a cumulative spell bonus?' and 'how happy am I going to be if I roll 12 on 2D6 whatever I do.'
At the same time, changing the damage a longsword causes or quickly typing in new values to differentiate more weapons by damage would be the preferred choice for any group that preferred those options.
