It's insulting and beyond ignorant to call CMU SCS, arguably the birth place of modern AI and software engineering a degree shop.
What's wrong that SCS selects academically distinguished students? Does not Caltech do exactly the same? BTW, outstanding ECs especially in mathematics and CS are the most important criteria to be admitted by SCS. It's students is now academically on bar with the students going to Caltech. Thanks for SCS's high academic standard for student admissions.
Now Caltech is less popular because many top students are less interested in it's theory focused curriculum and weak CS program. SCS is the leader in almost all CS fields, but especially in AI. This is demonstrated by CSRanking results. According to this ranking, its research capacity and impact, especially in AI, is equivalent to MIT and Stanford combined. It has arguably the most modernized CS curriculum, the strongest faculty and lots of research opportunities even for undergraduate students.