It's that simple.

He wasn't a technically skilled emcee, but he had everything else down pat: he was able to tell a story (which some of the most "technically skilled" emcees can't do at ALL), he was able to evoke emotion, he capably covered subjects that people were passionate about, his production was on point, he had charisma/humor, and most of all, he just represented a sincerity that people were ready to stand behind.

Every single one of those qualities shows on the songs - especially on the singles. The single selection for College Dropout was PERFECT. He didn't need technical skills, because he had literally every other category covered. There are more talented emcees who make much less memorable songs, and that's why he gets a pass.