No, I mean that 5e doesn't cover the same genre space as Cosmic Horror, and many of it's core genre logic parts actively fight against Cosmic Horror. Actually doing the genre of Cosmic Horror requires gutting so much of the 5e game that it would no longer be 5e.
I don't think anyone said vanilla 5e covers the same genre space as Cosmic Horror... but let's be clear the Mythos stories came out of the age of pulp and there was even cross-pollination with sword and sorcery, so it's not so far as to make 5e incapable of branching off into it. And no it doesn't really take gutting any of it only, adding to it.
I think the problem here may be that people are using the d20+mods vs DC with the GM deciding what happens is 5e, so anything that doe things this way is also 5e. That's an entirely facile definition, though.
You said Sanity and Madness. You can go back and look. I looked at Madness, because all Sanity does is change the lead-ins for the Madness rules. It's an optional subssystem for an optional subsystem. It does nothing on it's own without the Madness rules.
I already addressed this. Your complaint was that Madness checks used Cha or Wis which would give spellcasters an advantage that was inimical to the tropes of cosmological horror... I'll state it again (ands it's been posted in this very thread) Sanity eliminates that incongruity with the genre tropes in a pretty elegant and non-intrusive way.
I mean, you can be hurt that I didn't talk to the Sanity rules, but they are an option to an option. I felt dealing with Madness clearly and cleanly as the primary optional rule for these things was more direct to the point. However, sure, you've managed to point out that there's one argument of mine that can be addressed by adding a new stat to all characters, which has other knock on effects like making everyone MAD now, since the combat debuffs from the Madness systems should be prioritized to be avoided, and now you have the build question of whether or not those will be common in the game or rare, which is entirely up to the GM.
I'm not hurt, and don't address me or my emotional state... address the argument. So you're cherry picking to support your assertions. Because Sanity doesn't fit your pre-conceived conclusion that 5e can't do cosmological horror... it doesn't count. Really a Sanity check makes every class now MAD... by that logic every class is already MAD because there are spells and abilities that can affect any of their abilities to force a save in combat... You are seriously reaching Lol!! Why not just say my bad it does address that trope and move on?? I mean the game gives you extra points, an extra roll or an extra number for the array. So not seeing the major problem you are here.
Again, how do Flaws play? They aren't meant to be constant bits, but used to earn Inspiration according to the rules. You're now requiring a specific approach to play, one not even associated with a ruleset, to make the rules work.
Flaws are already a part of the rules. However nothing inherent in cosmological games necessitates long-term madness be enforced through in-game mechanics. We just had Cthulhu Dark presented as an example of a game that doesn't.
Here's a kicker -- I fully want players to fully inhabit and advocate for their PCs, to roleplay with integrity. But I also think having to tell a player how to roleplay is a terrible idea -- it's up to them to do this, it's their fun, not mine. If my game becomes ruined because a player has a different idea what roleplaying their character looks like, then that's my problem, not their. My goal is to have a game and system that encourages roleplaying, not one that demands a specific approach. I don't have a problem with roleplaying in my games -- my players are great! But I'm also not partial to telling them what they have to roleplay, ever. The Madness rules are telling players how to roleplay.
Honestly, if you're fully engaging the 5e rules, then the one bits of the Madness rules that actually engage roleplaying with integrity are the Flaws of permanent madness. These are incentivized by the ruleset via Inspiration. But, most people totally ignore this entire system, and instead rely on the GM policing proper roleplaying so that the GM can force roleplaying onto the players, like how the Madness system works.
I mean, look at Cthulhu Dark. It incentivizes putting your sanity on the line, but leave it as a player choice. The penalties for failing an Insanity roll is that you roleplay your insanity. How is entirely up to the player -- nothing is enforced by the GM.
Lol!! But you were just claiming there were no teeth to the madness unless there were mechanics that enforced the effects of madness... wouldn't that be telling your PC's how to roleplay? I'm a little confused on which approach you are advocating for? As for Flaws and inspiration and people totally ignoring the system (I'd love to get a proper poll going for this to get an accurate picture)... I would assume if you are using these rules... well you would use the rules in their entirety, what I can't speak too is how well the rules do when you choose not to follow them... at least that's not what I'm discussing.
Yeah, okay, those don't primarily hurt the combat pillar. Remember, without any immediate pressure the short term madness is over in minutes and so doesn't really matter. Long term, most of those are so debilitating that they incentivize sitting out until they wear off. I mean, if you have a few levels of exhaustion, which somewhat mimics most of these, you would take every action to remove them because they will get you killed in combat.
Come on, man.
Well duh, without immediate pressure the short term effects don't matter is missing the point... If I have an old god forcing it's way into our universe and need to finish reciting the ancient ritual in minutes to close the portal and looking upon it's dark magics just sent my character into fits of screaming, laughing, and weeping for 1d10 mins... well it could have a very big effect.
The same for long term, I would argue that if the PC's have the option to choose to sit out for months, until they feel better... well your issues have nothing to do with the rules and more to do with how you are choosing to run horror. Lol... you must run very laissez-faire & lackadaisical horror games.
I guess it's my turn... Come on, man.