Heh. "By the book, for the book and nothing but the book! So help me.... WotC." I will not post my "Three Stooges Paradox" I had distilled from past to present DMing, through the editions, here. That said I have stated and staked my position clearly and will add only this. Having followed the first link was but a reminder, nothing new. I've watched since the beginning and very closely so there was no surprise. What is forsaken by Player-Only agency is a worn topic at this point. It's been condensed to entertainment only, i.e., only having fun; and everyone is a winner of "fun". Fun has been defined as an irrefutable output by winning, not by playing or by any other measures that may, even incrementally, lead to mastery of anything sub to the point of winning. So if the system is devised up front to ensure winning occurs in each and every case, there cannot be (in the design philosophy so engineered/applied) interpreted DM agency of the finite system. The latter DM agency morphs into administrative roles in ensuring that the engaged system is working to its proper output from the designed-in inputs.
OD&D/AD&D are what they are due to overall system-capable elasticity.
The latter editions are what they are for the opposite reason. They are the finalized median view of the market. The market is about quickest throughput in all cases, from A to B to C. Elasticity is its polar opposite as that creates uncertainty in output. Is this a cynical view by WotC? No. It is a straight up market view and no one should be surprised by it in the least.
This isn't an argument by any means, but more a contrast: my preference, as a GM raised on 4e of all systems (sort of considered a high watermark for the player empowerment centric play) is for a relatively RAW experience, but modified by very intentional house rules (as opposed to on the spot rulings) that functionally create a variant game that adheres religiously to its
own internal RAW. Those systems can be elaborate, but I strongly desire that they be consistent and upfront so the players can plan around them.
Currently, I have a rules variant my players enjoy where Hero Points (an inspiration like mechanic that allows you occasional re-rolls, and awarded for things that might not be smart tactically but fit the fantasy) are given out via charisma at a rate of 1 + Half-Charisma-Modifier-Rounded-Down-- as GM I don't like arbitrarily giving them out, and its my mechanic for re-balancing the Charisma stat and making it useful (and therefore desirable) for all characters.
My game is also a 'variation' because it intentionally ignores the guidance the game we play has, that higher level characters can usually find magic items that surpass settlement level by leveraging their influence. I observed that mechanic to devalue crafting as written, and removed it to let the crafting system shine more.
Finally, I have an elaborate rules document in the works to support a West Marches style of play with the game-- defining treasure bundles to give guidance as to how to create treasure hoards that respect the spirit of WBL without actually adhering to it (ensuring that the extra wealth isn't an order of magnitude above), touching up the chase subsystem so they can be used on the spot to adjudicate escapes from higher level creatures likely to crush the party, as a consistent mechanic; Implementing reputation for a protectionist approach to ports where establishing a right to do business via permits is necessary to use it as a starting or ending location for voyages or to accomplish downtime activities there. Establishing a system through which treasure is used to purchase level ups directly (training, in the fiction.)
The game actually gives me guidance for most of these things-- the 'treasure bundles' are actually from a table in the GM book that is meant to allow the GM to award treasure on a per encounter basis, using the increments as differently sized chests of treasure appropriate to the level of the adventure, then allowing GMs (including myself and a few other friends) to use those bundles to construct treasure hoards of whatever size. The chase subsystem is present and based on a very hackable 'victory point mechanic' thats actually meant for the GM to develop their own subsystems based on it, so I'll just be adjusting it. Reputation is another victory point system, I know vaguely how many total hero points the party is meant to have through the advice given in the book for distributing them. Downtime is a core system and very well defined, so I just need to worry about how to track time and 'give out' Downtime (I'm thinking per session, since treasure is not a guarantee by design, it'll make a consolation prize.) The game has very basic rules for hexcrawling we'll probably flesh out a little more.
Even the way leads are going to have designated levels, balanced around 4 players of that level, and then stocked with treasure accordingly-- then intentionally allowing players to decide who they bring regardless of level, and allowing them to bring more than 4, without increasing the difficulty of treasure to encourage a risk/reward tradeoff where confronting higher level challenges is very rewarding, as is using a smaller group (since everyone's cuts are liable to be smaller) but might be more than the party can handle, is something that I can do because of how good the encounter guidelines are and how they account so well for number of PCs and level.
Whats lovely about that, relative to 5e, is that the game (Pathfinder 2e) gives me all this guidance that I can use to understand the 'design principles' of the game, and base my own variations off of. I'm reminded of opening ADND and reading Gary's advice for how to keep track of time in groups of players that don't all play together at once (which is something I did explicitly looking for thoughts on time tracking in this game, and informed my solution, despite it not being much like his.) There were all of these rules to adjudicate different things, and even if you didn't use them all (or at all) you could read it and use it to understand the game's underlying principles. Which is my biggest point of frustration with 5e, relative to Pathfinder 2e, or even ADND (which, I was born in 94, it predates me quite a bit.) I did the same thing with 5e (in terms of west marches stuff), and it was so much more frustrating to find any 'reasoned design principles' to anchor that too, and the work was so much more daunting.
TLDR: The takeaway, is that the 'player empowerment' style doesn't necessarily preclude GM agency, it just shfits it to a role of adding things rather than removing them, and to a 'houserules, not rulings' approach that rewards 'GM-as-designer.'