In a game with a pantheon, morality should be codified differently according to each God and Goddess. A single unified system of law/order/good/evil requires a single Absolute Judge.
No, it doesn't. I notice a lot of strict and unfounded assumptions in your posts. These signs of arrogance and a very self-centered personality are much more suited for being a NPC villain in this game than a questing party member. This attitude is a big red flag for being part of a cooperative game. And your suggestions here are extremely narrow-minded, which is confirming my earlier speculation that you're not bringing sufficient creativity to the game system. There are a lot of self-indulgent proclamations, but nothing intelligent.
Ad hominins are the refuge those without a reasoned argument. A universal system absolutely needs to be determined by a single arbiter. If an NPC is lawful good from one perspective, but neutral evil from another perspective, but chaotic neutral from another perspective, what result do you get from a successful Detect Alignment spell? The DM has to decide on universal alignment attribute in order for alignment mechanics to function according to RAW.
you insist that giving the players instructions to follow in regard to morality/lawfulness/chaos is absolutely essential. Presumably, because you don't see how such concepts could be addressed in the game without such instructions.
Lack of understanding of game design, and another irrational assumption. I've already corrected these errors in previous posts. I recommend going back and reading them.
Are instructions for the player to follow regarding alignment essential or aren't they?
This is nonsense. It seems like you are being willfully ignorant, now. The system is there to provide players with a way to add consistency and depth to what would otherwise be just this kind of tedious blathering. No one wants to listen to a blowhard drone on about personal opinions; they want to PLAY. Good and evil are intrinsic parts of the theme of the game, and have mechanical significance. Codifying them and giving them a connection to the game is welcomed and enriching. It's up to the player to get over themselves and use the tools provided to play the game with other people, who are also following the same rules. You can save the college freshman philosophy talk for after D&D is over.
Ad hominins are the refuge those without a reasoned argument. Why don't you give us an example of how alignment mechanics "add consistency and depth"? Explain why it is necessary for Bards to be "non-lawful." Is it because music and storytelling are crimes throughout Toril? Is it because writing a 25 piece symphony or compiling the histories of civilization requires an undisciplined mind? What does the alignment restriction on Bards add to the game? How does that make the game deeper and more consistent?