Hey, I read your alignment-fix-post, and it was interesting! I'd never heard it explained so cogently before. What I'd like to know is,My question is why do we need the system? Isn't it just an attempt to unnecessarily apply mechanics to a social feature? If there's a drive in players to differentiate from one another (and I'd argue there is), they are encouraged to oppose one another fundamentally, making cooperation nigh impossible/group dynamics super fraught. Why do we need alignments?
A fair question! And the simplest answer, in all honesty, is: we don’t. There is no need for the alignment system. Once upon a time it served mechanical benefits (detect good/evil, protection from good/evil, etc) but those have been removed and/or completely retooled by later editions. And wisely so, IMO! Because of the exact sort of interference to cooperation that you’re mentioning.
I’ve even got some notes on that post that (rather rudely, honestly) said a better idea was to toss the alignment system all together. And like: okay? You don’t have to use it. It serves no mechanical benefit. If your game group doesn’t want to use alignment, then feel free to toss it out! Anyone who gets a bug up their butt about you not using alignments (oh the wank when 4e tried to change that up) needs to chill out and maybe reevaluate their priorities.
What I would argue, though, is that it does serve a potential purpose as an RP guide. If you’re new to RPing and not used to trying to stay in character and something comes up that throws you off, there’s a simple guideline to say “how would me character act here?” Or say you’re a DM running a prewritten adventure: you’ve been handed some NPCs and a script for them, and your players just jumped track entirely. How do the NPCs respond? Here’s a quick cheat-sheet.
Or maybe you’re really into worldbuilding (as I am). The generic orc stats say they’re chaotic evil. What does that tell me about their society? I hate a lot of the details D&D has published for the orcs (Volo can kiss my ass), but I still want to flesh them out in a way that will be recognizable to my players. Those two words (chaotic evil) can help act as a guidepost for keeping stuff recognizable even as a I do whatever I want.
Etc etc. You don’t even have to be a beginner RPer, plenty of experienced RPers use different tricks to establish their characters in the first place. Sitting down with your new character and thinking about what alignment they’d be can be a good way to figure out what their ideals are and what they’re willing to do for those ideals. Hell, 5e added the personality traits/ideals/bonds/flaws thing, and it serves no mechanical purpose. Yes, yes, it theoretically grants Inspiration, but I’ve seen people leave those sections of the character sheet totally blank. It’s an RP tool. Since it no longer serves a mechanical benefit, people can feel free to use it however they like.
And then of course there’s the fallback that it Just Doesn’t Feel Like D&D Without Alignments, which is silly but definitely a feeling people (including me) have. But ultimately for me it’s this: the alignment system, for good or ill, has spread out through cultural osmosis so that people use the terms in completely unrelated settings, and it is probably still going to be around when we hit D&D 20e. It’s not going away. But it is getting more complicated and confused by different interpretations of it and confusion over the terminology, so occasionally pruning back the growth and simplifying back to essentials is a good idea. I like it as an RP guide, but it’s a useless RP guide if you can literally argue any character to fit into any alignment bucket.
One last note: while the original alignment stuff definitely included a fundamental divide between the extremes of the table, that’s dropped by the wayside (at least on the lawful/chaotic axis) and I think that’s a good thing. You’re right that encouraging polarization in the characters is a bad idea. There’s a reason I didn’t bring that up in my fix-it post, and that’s that I think it’s a relic of a bygone RP age and good riddance. Besides, there are literally BECMI era books that have lawful and chaotic people partying up together, so clearly the creators were never actually that married to the concept of individuals taking sides in a cosmic battle, either.