It's under the same heading you quoted -- the role of the dice.
EDIT: and no, not right not, I'm away from my books.
I didn't pull my excerpts from that section it's a totally different topic but ok... let's take a look at it.
This section appears to be a set of options for the DM to decide what role the dice will play in his particular game...
The Role of the Dice
Premise: The dice are neutral arbiters... the extent to which you use them is entirely up to you.
Ok so the extent to which you use the dice will be decided by the DM... make sense since you can say yes... say no or require a roll, nothing too amazing here.
Rolling With It
-Some DM rely on dice for almost everything
-When a character attempts a task the DM calls for a check and picks a DC
-Can't rely on the characters succeeding or failing on any one check to move the action in any one direction
-Must be ready to improvise and react to a changing situation
-Drawback: Roleplaying can diminish if players feel dies rolls determine outcome more than their decisions
The very first thing I notice with this option is the word usage of "almost" everything. So even these options are acknowledging they are not absolutes, and so with that said... I still see the principles I discussed earlier being used with this choice. Majority of the time the DM's answer will be roll for it but rarely they will invoke Yes or No.
Ignoring the Dice
-Use dice as rarely as possible
-Example: Some DM's only roll for combat
-DM decides whether an action or a plan succeeds or fails based on the players making their case
-Example: describing searching for a secret door in the correct spot and twisting the correct sconce to find the trigger
-Rewards creativity by encouraging players to look to the situation described for an answer
-Downside: No DM is completely neutral
Again I notice the conditional wording... "as rarely as possible". But even more telling is the example of the secret door they give... what this style seems to be suggesting to me is that the decision points in the game will almost always be framed in a yes/no choice for the players actions from the DM but there will be smaller fringe cases where the DM will still use the dice. Again not seeing how the guidelines don't apply here as it's not actually supporting no dice rolls whatsoever and implies there have to be clear and definite yes/no answers for what the DM does rule on without dice rolls.
The Middle Path
-Using a combination of the two as the best approach
-Strikes a balance between players relying on their bonuses and abilities and paying attention to the game world
-At any time you can decide a players actions are automatically successful
-You can grant the player advantage on any ability check reducing influence of a bad die roll
-You can grant disadvantage to transform the easiest task into a an impossibility
This uses a mixture of both so the guidelines apply.
Honestly I feel like you are really overstating this DM can do whatever they want thing. They are optional approaches to minimize the usage of one aspect or another...but nowhere in the section on "Ignoring the Dice" does it advocate for a DM not to roll at all and nowhere in the section on "Rolling With It" does it advocate for a DM only ever rolling dice. The wording, examples, etc are very specific in avoiding an absolute.