Disclaimer: I graduated from Georgia Tech
This is how introductory (freshman/sophomore-level) classes are taught at almost every mid-to-large size university. There are simply too many students taking these classes to do it any other way. At Georgia Tech, for instance, every undergraduate student (management and business majors included) are required to take Calculus 1-2 and Physics 1-2. At GT, that's about 1500 students per semester that have to take those classes.
During these classes, the professors lecture (aka teach), and you're expected to either learn it then or to do something we call "studying" until you understand the material.
I'm not saying it's right or wrong, it's simply the only feasible way to have that many students take the classes from a qualified instructor (professor). There would be even more bitching and moaning if it were Teaching Assistants actually in charge of the class, rather than just the recitations.
I can not think of a single class I took at GT where the lecturer (even in the large undergrad classes) simply droned on and on without making a good effort at explaining the material in a way that someone unfamiliar with it (a student) would understand. The vast majority of professors/lecturers were interesting and engaging. Furthermore, virtually every class in my major (and all junior-level classes and beyond) that I took had class sizes less than 50, and most were under 30.
It's not like high school, where during Math class the teacher would say to everyone "ok, now work this problem and I'll come walk around and watch over your shoulders!". You're not going to be able to absorb and internalize all the material just from sitting and listening/participating in class. You don't work problems during lecture; lecture is for presenting you with the material, and it's then your responsibility to make sure you understand what you were taught. Professors assume you are mature and capable of determining if you need to do extra work outside of class or not. To this end, most instructors don't assign mandatory problem-sets to babysit your learning, though many do offer suggestions of problems to work outside of class.
Take some fucking initiative. At a university, you have to actually spend some time and study if you want to succeed.
> Now maybe this is by intent - maybe the idea is to weed out everyone who isn't smart enough to learn the core material on their own.
To address your concern more directly: yes; to a degree, that is one of the many purposes of a college degree. You're not going to be able to scrape by in any technical field based solely on what you learned in school; you have to be constantly learning. Universities teach you a base level of information relevant to your field, but perhaps more importantly: they certify that you're capable of quickly learning and understanding complicated material.