I'm saying that having a string of encounters that aren't taxing or challenging beyond accounting details would be boring. You don't get to dismiss that with irrelevant arguments.
You said 'some players' might find it boring, and that's true. For any given way you might play the game, there's probably some players out there who find it boring. If your assertion that a string of 'standard' encounters would always be boring to everyone, obviously, you're just wrong. Tastes just vary.
Neither case really matters. It's legitimate to want to play an RPG in variety of ways, including with very different pacing, possibly within the same campaign.
The point is...
But that's my point. Since the game is not flexible in this way, it works only for a specific kind of scenario.
And it's a perfectly valid point. But, it's not that hard to get around the inflexibility of the system, by being flexible, yourself.
If you meant you agree to my point about the need to "other ways you might want to pace a story" and have rules that are "flexible about what constitutes a long or short rest" then alrighty.
Except for 'have rules,' that was it, yep. The rules give you a time frame for a short and a long rest. They also give the DM unlimited licence not just to change the rules formally (house rules/variants/modules) but to make rulings on the spot that don't necessarily follow the letter of the rules...
not sure what point you're trying to make. Other than "yeah, well, the rules are flawed but since us humans can work around the kinks they're not really flawed, they're perfect" which I hope you're not saying?
No, I'm not going all Oberoni Fallacy on you.

But, it's also not really the Oberoni case of changing the rules if you're just 'working around them.'
5e design doesn't try to be perfect, nor even all that 'good' by any objective standard, they're just a starting-point for the DM.
So, yes, the rules are inflexible when it comes to pacing, if you follow only the letter of the rules on how long rests take. No, that's not a 'flaw,' because the rules also let you make rulings about whether the PC can get the full benefit of a rest or not in a given circumstance (indeed, make rulings about anything, irrespective of the letter of the most-applicable rule available). No, that doesn't make them perfect, just intentionally limited in what they try to do and designed to be dependent upon the DM for functionality/playability.
When you run 5e, you're not just signing up to RP NPCs and run Monsters, you're also acting as a critical part of the system. Without a DM willing to make rulings, yes, you'll just be playing a hopelessly 'flawed' game.
When D&D first came out, it was a pretty 'flawed' game, because it was a new kind of game, and no one new how to make a working one. DMs fixed it up on the fly or re-wrote it wholesale because they had to in order to run a successful game at all. 5e intentionally harkens back to that style. Then, it was because there was no other choice. Now, it's because it's fun. It's not like there haven't been plenty of complete, balanced, clear, consistent, RAW-playable RPGs produced since those early days (arguably, a past edition or two of D&D may even have qualified), but if we're playing 5e, it's because we want that D&D experience.
Sorry if that got a little too nostalgic and philosophical.