The people I worked with typically wanted to see students succeed. It went well beyond the mechanics of delivering instruction and assessing work. They considered what they were doing and put time into modifying their practices when students did not appear to be engaged. For a handful of students, it would be successful. In the vast majority of students, it would flop since the disinterested ones were rarely receptive. Some cases may have been similar to yours, where it sounds like you were focusing on other subjects. Some students appeared to be, ahem, more interested in the non-academic merits of university life. It is difficult to tell what the breakdown is since those students were always the most distant. But either way those passive students were a drain. They simply weren't as much of a drain as the cheaters.
Teachers need to design their programs around actual learning principles like: Deep Processing, Chunking, Building Associations, Dual Coding, Deliberate Practice.
Is this really an issue? I eventually feel into that bucket. Went to university for EE since I figured I could teach myself CS easily, whereas learning EE without a lab would be harder. I quickly realized I hate a very large portion of EE (anything outside semiconductors) and for most of my courses I did the bare minimum to get an A with minimal understanding.
> They go from being passive leeches on the system to actively destructive forces.
I really don't see how that makes me a passive leech. I agree that cheating is actively harmful to the peers that don't cheat, but someone that doesn't engage is a net gain to the others in my book. By not attending any optional tutorials/office hours it gives other peers more focus time with the professor/TA.