But that's not a counterargument. Your simply restating your own point, which I disagree with. It's pretty obvious that someone who would score well in an artificial testing environment A would score well in such an environment B if B is a followup of A. That doesn't disprove the point that grades are a fundamentally flawed concept in education.

>My personal experience is that tests are an effective method of determining who should proceed and who should not.

Again, based on what? Conformance to a completely artificial testing environment? Again, tests have nothing to do with reality and are a flawed concept. If anything, they show if you can work under an extreme time constraint with limited resources available. Are we really basing success or failure in all of our education on this limited and arguably pretty unimportant skill-set?

>Lectures do work. They have been working for hundreds of years. This isn't an appeal to tradition. This is a statement about evidence that they work.

You're still ignoring the context, and that is that we have a better alternative to physical lectures now. Let me present an analogy:

"Books work. They have been working for hundreds of years. This is a factual statement about evidence that they work."

While principally true, that doesn't change the fact that printed letters on dead trees are no longer a viable model of distributing knowledge. It's an appeal to tradition because you ignore the context at hand. Your only argument is "we've always done it that way, therefore it must be right, why change it?".

>Lectures work so effectively that people want to put them online so anyone can watch them.

What are you trying to argue with this? Yes, online lectures are better than traditional lectures. To extend on the book analogy, while it's fundamentally still the same as reading a physical book (you're parsing words), an electronic representation of text is in every way superior to a printed book. The same holds true for online lectures.

>They won't sit through a 20 minute lecture on how to solve quadratic equations. (Except a core group of good students.)

Let me present you with my anecdotal experience as a student myself: Next to no one but a core group of good students will sit through any physical lecture unless it's absolutely mandatory to attend, either. As I've put it in another comment, if you're not at the university because you want to learn, what the fuck are you doing at the university?