Or a rogue...I also would not cast Smaug as an Ancient Red Dragon. Generally nothing seen in Middle Earth can't be accomplished in the first 10 levels of the game.
If Bard is a Ranger it would also help explain why he could put so much power into a single arrow.
If the adventure or DM put in a hard block that can only be solved with a 20, doesn't allow rerolls, and has no alternate way to move forward in the adventure - that's poor adventure design, has nothing to do with the game system.
Now we have a case where even a 20 won't handle it, and that stays true. It's bad adventure design or DMing, has nothing to do with the game.
And if it's a combat and the characters can't hit on a 20, perhaps the players should not assume everything they encounter is a fight they can win and instead retreat. With the same caveat - if an adventure has an unbeatable monster and no reasonable way to win via alternate methods or retreat, it's a poorly designed encounter.
I disagree with your analysis on this. Let's say at low levels the players face defeat at the hands of goblins. And the players swear some day they will return and kill all the goblins.
Fast forward, the players are now all high level. And they say they want to go back to the goblin nation, and start killing all the goblins.
This is not "adventure design" it's "ordinary sandbox play". The world doesn't automatically increase the difficulty level of challenges in an area just because the players enter it, like a video game. If that's the goblin nation, composed almost entirely of low level goblins, and the rules state the goblins literally cannot hit the players even if they roll a 20, that's a RULES issue that is breaking immersion, not a DM or adventure design issue. Any sort of fantasy or real world laws of physics should state that someone can get a lucky hit, and that hordes can overwhelm individuals even if each member of the horde couldn't do it alone. The rules should, in some respect, account for this. The DM should not need to design around it.
I disagree. You are mixing up "real world" hit which mean contact, and PF hit, which also adds penetrating armor. I can take a stick, swing it at the WW2 tank that's an exhibit at a nearby part, and I don't care if I do it 20 times of 100, I can guarentee that it will not penetrate the armor to do damage to something inside. And yes, high level characters with magical defenses are like that tank.
So it might be that there is a rules issue, but it's with defenses generating "misses" in the first place, something in place with both versions of PF (and every version of D&D both before and after).
I am not even sure how this is a controversial issue. I know people get super passionate about rules, particularly new rules which are under fire, and I can appreciate that as I've experienced that sentiment myself before. But I feel like this is pretty objectively a rules-oriented discussion and not something people should bash DMs or adventure designers over. If you're OK with something being just entirely not hittable at all, that's a fair opinion. But I don't get the bashing DMs and adventure designers over this issue - PF2 made a rules-oriented choice about this. Adherents to PF2 should be able to defend that rule without turning it on players of the game for not finding a way to work around the rule. If it's something players need to work around, that's a pretty good sign it's the rule that's the problem.
This is a d20 system. If something would happen much less than 5% of the time, then it's too rare to show up in our statistical model.You should be able to hit anything, with really very good luck. The odds might be drastically, overwhelmingly against you, and you might do little damage, but you should have a chance. If PF2 has built a rules-based system which says you simply cannot hit something, ever, no matter how much luck and fate is on your side, I'd say that is very clearly a rules issue and not a DM or adventure design issue.
Sure, but I don't think you will be getting that in D&D either. Bard the Bowman made the shot with a non-magical bow and killed the dragon, despite a longbow only doing crit (1d8 + Dex) x 2 damage against an ancient red dragon that was previously at full HP. Even with bounded accuracy, I don't think D&D is meant to support these sort of stories.