There's no way, with all the techniques you need to be a base level RA, you could learn everything you need on the job.
And, I might add, who says the techniques taught are the most efficient way of doing things? Whre do new techniques come from? Research. Where do you get a qualification which enables you to perform research? Uni.
If you want to argue real-world experience with other courses like international studies, computing or media, go ahead. But it's absolutely untrue for science. The level of knowledge expected in a scientist makes doing it on the job pretty impractical.