Idk, then you are more skilled but the enemies are also more skilled. How is that conceptually different?
It's conceptually different because it's not an abstract number. What does "Level" mean in the game world? If you were a character in the game, you wouldn't say, "Wow, he's level 15!" Level is an abstract number that is only relevant to a player. Skill, on the other hand, is not abstract (nor is it a number. Although it could be represented as one.) Say you have a spear. This is your first time picking it up. All you can do is poke people, but then you practice and become more skilled. Now you can poke people and throw it. Then you become even more skilled. Now you can poke people, throw it, and hit two creatures with one strike (like going through one person and hitting the one behind him). That's different from level, where your "Strength" increases one point and your "Dexterity" increases 2 every time you level up.
This is not to say that skill can't be represented by a number, say at Skill 1 you can only poke and Skill 2 you can poke and throw. This is just to explain how it is different than "Level"
Idk, then you are more skilled but the enemies are also more skilled. How is that conceptually different?
I think/hope he is talking about a more qualitative advancement.
Your hope is well-founded, although a quantitative representation is usually helpful.
I totally agree that this is a more interesting type of advancement, but my point is that you could count up the number of things you have gained and still call that level. And I would say having that number visible to the player is a good thing. It's a solid number that represents overall gains. One lvl 17 player may be totally different than another lvl 17 player, but it tells you some kind of measure of how much they have done in the game.
I agree with you too, and it is true that having the number visible is a good thing, but, if you are growing qualitatively (or Skill-by-skill, which seems a little more layman's-terms-esque), it can be hard to represent where you are and what you can do with a single number.
Take for example two characters. Both are level 7. From that single number, you might think that they are exactly the same, give or take a few equipment choices or something along that line. But, if you look deeper, you might find out that Player 1 has grown in stealth, and speed, and thrown weapons, whereas Player 2 has mastered the art of magic and sorcery and summoning monsters. I think the best choice is to list the character's class (or equivalent) and the level.