For quasi-deities, these characters sure are living a banal life.
Well, they are powerful....but there are many other people out there nearly as powerful. And let's be fair about their life if you followed them in my game:
"A bunch of adventurers looking for work were asked to deliver a package to someone in a village. They found the guy missing and uncovered a plot to destroy the world. They tried to warn people but no one would listen so they spent the next year of their life waging guerrilla warfare against the enemy's stronghold, killing off and defeating the cult until the threat against the world was no more. When they finish that, they found out they had extraordinary powers...but still didn't have any jobs. Someone came up to them and offered them a position in a group called Barricade that protects the world against extremely powerful threats and acquires extremely rare items for people with enough money. Their first assignment: find a magical item from the bottom of a dungeon created by one of the most powerful families of Wizards ever to exist."
Good thing their only goals involved challenges that don't anticipate their abilities, react to them, or preempt them!
Just like the challenges they faced before that. And the challenges I faced the last time I played a game. Also the time before that. And every game since I started playing D&D 20 years ago. In fact, I can't think of a single time the enemies reacted to our abilities or attempted to preempt them.
We've always played that the PCs are exceptional. Their abilities are all but unknown except for the most powerful people in the world. There are powerful people, but most of them are just really, really good at fighting. Wizards and spell casters are 1 in 100 or less than that.
I think of it the same way I think of the Forgotten Realms novels. In them, Bruenor Battlehammer is the king of Mithril Hall. He was listed as a 13th level fighter in the 3e FR books. He is likely much higher level by the time some of the later books happen. He has no idea how teleportation magic works. His kingdom isn't especially warded against anyone teleporting in. He has some Clerics in his Clan, but almost none of them are as powerful as he is. This is a major Dwarven kingdom, as well. Drizzt is equally high level and knows very little about magic.
When they fight Wizards, they do so by dodging out of the way of their spells and killing them with pure swordplay. There's no anticipating their abilities or preempting them.
They also fairly often stay in inns.
Reminds me of a great Star Trek episode I saw once where a couple of cadets stole a shuttle, used the transporter to beam into every bank on planet Earth, vaporized the doors to the vaults with their phasers, and beamed back out with all the money in the world with no one the wiser. It was just that easy!
To be fair, it would likely be that easy in the Star Trek universe, what with the whole "Humans have evolved beyond crime" thing they have going on. No one would expect it or likely have any defense against it.
Still, there's a difference between technology and magic. In Star Trek, there are likely millions of engineers that are inventing things. The things they invent are instantly transmitted to everyone else on the planet via a world wide communication network where they can be replicated for free. If there is a device that prevents someone from beaming into a bank, it's likely every bank in the world has one. This is because everyone in the world has access to transporter technology as well for the same reasons. You don't need to be an engineer to acquire or use any of these devices.
In D&D, magic items are created by wizards who are a very small percentage of the population using an art steeped in mystery and obfuscation. These wizards are jealous, secretive, and loners by their very nature. Creating magic items, depending on the edition either requires quests that can take a year to finish and require risking your life against extremely dangerous creatures(2e) or require putting your own life force into the item(3e) and likely also cost extremely large sums of cash. Even if one invents a way to stop teleportation, its likely not every wizard knows this secret. Even if they did know the secret is it worth the time and energy to make such an item or ward a place against it when there are very few people in the world who are powerful enough to cast such magic?
These kinds of protections aren't the sort of thing that you'll find at every bank or every monster lair in the world. Even the powerful ones. Just because the book says there is a spell or magic item to protect against something, I don't immediately assume the bad guys have it. In fact, rather the opposite. I find the specific creation of counter measures against the PCs' abilities to be rather contrived and unlikely without a REALLY good reason. If the bad guys have a powerful wizard and I've decided he knows the spell that would counter the PCs and he has seen them use it before and they've given him reason to believe they'll be back AND they give him time to cast it...sure, they might be countered.
I don't consider this to be a "default" position by any means. At least, not according to the lore and setting I envision D&D taking place in.
Well, there's a problem. I would definitely not expect a published adventure to work at that level (or any level really, but especially not that level). It doesn't sound like it really leveraged any of the things you can do to players at that level.
Oddly enough, I took the magazine at its word when it said "For adventurers level 15 to 19". I assumed they were publishing adventures that would work fine at that level. The DMG didn't tell me I needed to do anything special to run a game at 16th level vs 1st level. It said to pick monsters of the appropriate CRs and use the same combat rules I'd been using since the beginning.
D&D never told me there was some sort of special procedure I needed to go through to run a high level game. I figured that since the magazine was being published in concert with the people who created the game, they would know if published adventures were a bad idea and wouldn't publish them if that was the case.
This is true, and this is where the CR system fails. A dumb brute (with special exceptions like the Tarrasque) is simply not an appropriate challenge for high-level characters (of any class, really). This isn't a flaw of the rules for creating monsters, but the guidelines for using them. I assure you, the rules provide for creating some much better monsters.
The brute monsters worked just fine as monsters against the non-magic classes. It was only the casters that often made them useless.
I'm not sure how using them differently would matter. The monsters themselves were kind of useless against casters. They were monsters that were published in Monster Manuals and labelled specifically for high level play.
I'm sure there ARE rules for creating ones that work better. However, I'd rather not limit myself to a small collection of monsters out of all of them that are available simply because spellcasters were created with poor balance in the game.
I mean, are we really in a thread whose topic is "There were no real problems with balance in D&D, it was all academic" saying "There's no problem at all with spellcasters, you just needed to restrict yourself to 5% of the monsters that can handle them properly, design adventures specifically to counter all their abilities and never run published adventures ever. But not because there's an issue with balance...but because.....reasons..."