A professor cannot teach 300,000 people.
Of course not. But 300,000 people can watch one professor's lecture. Teaching is more than just lecturing, but by delivering the lecture to a mass audience, you can divert a lot of resources into other aspects of teaching.
That's nothing more than a video presentation, which no more replaces an actual teacher than a book is a substitute for a class.
So do you also think we shouldn't use books?
What you're describing isn't bringing technology to school. It's just using technology to send information.
No it isn't. You should visit a modern "flipped" classroom. The students watch the lectures online at home, and do the "homework" at school. The teachers don't lecture, they teach , mostly one-on-one with any student that is having problems. By using mass lectures, you are not commoditizing education, you are freeing up resources so that you can customize it for each student.