My uncle made me do the same thing with an old Mauser action. Spent hours with a file and stone, just trying to get that butter-smooth feed. Now everything is pre-fit and shipped in two days. Where's the pride in that? Does anyone even know how their rifle truly works anymore? That hands-on time taught me more than any manual ever could.
The real loss is the problem solving. You learn why a round hangs up, not just that it does. You figure out if it's the extractor, the feed ramp, the magazine. That's knowledge you can't get from a drop-in part. It turns a jam into a puzzle instead of a call to customer service.