So the 2024 rules has optional rules (things you can add to augment certain things) but not optional systems (things that change fundamental aspects of the rules). For example, it gives all the traditional optional methods for generating ability scores, but does not give the option for a 7th (or more) ability score like Honor or Sanity. The latter is a fundamental change to the system and requires a DM to do more than just add another score to the PCs 's sheet. (How does it interact with skills, saves, magic like enhanced ability, etc). That's a major amount of adjudication and rulings a DM has to make that aren't covered in the page and a half both ability scores are given in 2014. The ramifications are far larger than the rule appears.
The same is true of changing the skill system, making slots into spell points, or mucking with the rest mechanics. We, having played for a long time are comfortable with adjudicating such changes. But the game should not present such options to newer or less experienced DMs without fully explaining the ramifications of such changes. You need more than a few paragraphs to explain that changing the resting rules will change encounter balancing (and make that part in the DMG moot) or how spell point flexibility allows for more firepower than the game assumes for a given level. In short, those optional systems make much of the stuff they just learned in the DMG invalid, and I can understand why WotC would choose to exclude them.
Maybe we'll get a big book on optional rules where each one can be explained in greater detail and given the space needed to explain how it changes the game besides the obvious ways. Maybe WotC will cede that space to 3pp. Regardless, it's probably for the best that the book that is tasked with teaching the game doesn't also give options to break it without proper explanation on what and how it broke.