>Moreover, the leveling mechanics are such that the things you do to attain levels are only loosely correlated to the skills you obtain from those levels, e.g., why would killing a bunch of kobolds suddenly allow you to cast two fireballs instead of one?
Interestingly enough, this is subverted in the first edition of AD&D- XP for killing was negligible, you got most of your XP based on gold/treasures amassed, once you hit the XP requirement for the next level you had to pay a mentor or trainer NPC ridiculous amounts of gold to have them train you for in-game weeks to actually gain it. If the DM felt that your characters play style did not reflect your classes archetype in a way that would allow them to "learn" ie if you played a magic user and never cast spells or used magic items he could deny you the level outright or impose a leveling or XP penalty on you. But understandably enough getting a report card from your DM every session on how you're playing your character "wrong" wasn't popular enough to stick around as a mechanic.
Interestingly enough, this is subverted in the first edition of AD&D- XP for killing was negligible, you got most of your XP based on gold/treasures amassed, once you hit the XP requirement for the next level you had to pay a mentor or trainer NPC ridiculous amounts of gold to have them train you for in-game weeks to actually gain it. If the DM felt that your characters play style did not reflect your classes archetype in a way that would allow them to "learn" ie if you played a magic user and never cast spells or used magic items he could deny you the level outright or impose a leveling or XP penalty on you. But understandably enough getting a report card from your DM every session on how you're playing your character "wrong" wasn't popular enough to stick around as a mechanic.