Not all of them are. At least my old one was way louder than my current. Same price range, too ($20-$30 I think, both were presents). I think I could use this one in my kitchen without waking up anyone. There's a good possibility that the old one was also noisier just because it was getting old and perhaps rattled a bit. Both are blade grinders, maybe burr grinders are louder by nature. I think if I really wanted it more quiet I could even wrap it in a towel or pillow :-p
I share a bubble with eterm, in a Fortune 100 enterprise. I have heard React mentioned once by a particularly engaged front-end developer, but everything I know of in production is JQuery, a couple Angular 1 apps, and a whole lot of horrible older stuff.
Line height isn't really solved by a one size fits all solution. Each font size should have it's own line height that is proportional to the size of the text.
Bio: I am a self-taught full stack developer with a over a year of professional experience looking to move from full stack to focusing on the front end.