Campaign pacing is not necessary.
Events which proceed in a sequence by definition have a rate at which they occur, and thus a pacing (which, if I had to give it a rigorous definition, is something akin to frequency, e.g. event-cycles per time, though the relevant aspect is the human perception thereof). It is not possible to conduct a sequence of events, plural, and have it fail to have a pacing of some kind. (A sequence of one event could be said to have no pacing, as it has no defined time between events, but I would assert that few games manage to be singular events!) The pacing can be chosen or allowed to simply happen, but either way, it happens.
The first casualty of any war is the plan, including the DM's plan to have x encounters per day (and specifically, these specific x encounters per day). By definition, the players are going to mess up the DM's plan, so there is no real need for him to plan how many encounters. Just prepare the adventure with the encounters and as the players get to them, they get to them. Granted, if there is some form of time critical situation, then if the players rest, they will face the consequences of doing that.
This strikes me as an enormous fallacy. "Plans cannot be perfect, thus plans should never ever be used in even the smallest degree." The perfect is the enemy of the good; just because it is impossible to plan for every possible detail does not mean that plans are worthless. Plans can and should be made, as long as they are flexible. That will, of course, require that the DM (and the players) think on their feet, rather than slavishly obeying a wrote script--but I sincerely doubt that anyone who thinks campaign pacing is important is slavishly devoted to scripts, if only because that requires an
extremely uncharitable perspective of one side of the discussion.
Why? The only time it matters is if some one player is more concerned how much other players shine. So what if we rest for the fighters? It just means that the fighter is now more capable for the next fight. None of the players at my table would care. They do not consider the fighter player to be dominating play. They consider the party to be more effective if everyone has a lot of options.
It might be different at your table.
So you're saying it is
utterly impossible for one person to feel like they couldn't contribute enough to make a meaningful impact, while others were able to solve problems (be they combat or non-combat) almost singlehandedly? That it's
impossible for one person to feel sheepish for always being the "I Win button presser"? Because you can easily have such a situation in a game where the rest cycle favors one group over another, and (apparently) 5e keeps its line rather close to points of divergence. What I mean by that is, having
zero short rests per day pretty thoroughly shafts certain classes but not others, while having four or more pretty significantly empowers those classes, yet that's a difference of only +/- 2 from the number typically recommended.
Why? Can a DM not be good and still ignore that stuff? Sure he can. It's unimportant. Just because it is written down in the book does not mean that a DM should be a zombie and follow it verbatim. It's a guideline. Use it. Don't use it. It doesn't matter. Fun can still be had regardless.
Depends on what you mean--and whether "be a good DM" is all and exclusively what a group needs. I would assert that there is more than that. You can have a good DM and still have a poor game experience if the game doesn't enable you to participate. Having a drought or surplus of resources is precisely the kind of situation where
even with a good DM, people can end up unhappy.
So...yes, "slavish" devotion to resource schedules is unimportant for "being a good DM," but "being a good DM" is not sufficient for "everyone at the table has fun." It's a big and useful step in the right direction, to be sure, but that alone isn't enough--and a DM aware of the impact of variable resources will understand that.