That's true. It doesn't work against things it doesn't work against, but that doesn't change with level. How often you encounter effects that it doesn't work against depends on the DM.
That's where the fallacy is. It is just as effective as before. If it knocked 3 off of 30 or 3 off of 3, it's still 3 less damage in total per hit.
It's utility doesn't change.
At higher levels it knocks less off of the total of each, but at higher levels you have a bigger hp total to absorb it with and it evens out.
I can tell you for a fact having a DR 4 on my paladin in a 4e campaign
If it reduced damage by 100% in one instance, and 10% in the other, then it is correct to see it is less effective in the 10% than it is in the 100%. That's not a false argument. "Effective" is a word that scales, as some things are more effective than other things. In this case, the feat is more effective at preventing percentages of damage when the damage being done in the first place is low.
While this is true, foes rarely do 30 points of damage in a single attack, even at higher levels.
Exactly. If anything, what we're seeing is how powerful the human variant is at 1st level (and how that power tapers after everyone else starts getting feats, too) and how problematic 1st level can be, in general, with characters being so fragile.Some feats are too strong at 1st level; almost like they designed the game for feats to only show up starting at 4th level.
It's fine after that.
KD, we were comparing a specific set of creatures - kobold to dragon. It would not be unusual for an adult red dragon to do 30 points of damage (I roll for damage, as do a lot of people, and that is quite well in the damage range for a single attack).
He said it would be exactly equally effective against both, and I was disagreeing with him. And, you seem to agree with me on that point (as you started by saying "that is true").
The same of course holds true for other levels in my experience as well. Preventing 100% of damage from a kobold is a lot more effective than preventing 20% damage from something that hits for 15 points damage.
Our fighter, who has the feat, barely noticed the benefit when fighting hill giants. I was talking from direct experience - one of our fighters has this feat, and as he's gotten to higher levels (we're only 6th level now) it's become less effective, with fewer creatures even doing that kind of damage. It's gotten so bad he's been asking me if he could switch the feat.
It might be possible, but it is still not likely.
It is even not likely that most battles will be with anything nearly as powerful as an Adult Red Dragon
Odd. Maybe you have a player who forgets that he might not even have survived to 6th level without the feat.
A bite does 2d10+8+2d6. Assuming the fight lasts more than a single round, it seems quite likely an attack will do 4 points more than average at some point.
KD, you jumped into a conversation about that example, and now you're trying to retroactively change the conversation we were having to something else. The response you quoted was about that example, and both parties were talking about that example. If you want to talk about something else, that's fine. But stop quoting me in doing it, as you're trying to change the context of a quote after it had already taken place.
I don't think it is odd at all. How much experience do you have playing with the feat, as opposed to theorycrafting about it? We have some armor that does this as well (Black Dragon Scale Mail from the playtest docs), and so I have two things in the party to compare it to, and we've found a lot of attacks simply don't trigger this feat at all. So what is your actual play experience that differs?
But 30 points of damage is the exception by a lot, not the rule. Very few creatures can even get that high with a weapon attack and very few encounters in the lifetime of campaigns starting at first level are with those types of creatures.
There might be a dozen such creatures in the entire monster manual out of over 300 creatures.
Yup. The one encounter in a hundred Adult Red Dragon can do 30 points of damage with a single attack one round in three.
Your point?
Everyone jumps into other people's conversations, yourself included. That's called a conversation.
Our 3rd level PC fighter has the feat.
Theorycraft my butt. My experience is just as anecdotal as your experience,
Very few monsters in the MM usually do about 3 points of damage or about 30 points of damage.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.