My guess is that not many people changed phonograph needles nearly that often back then. Obviously, many of the 78's you hear on youtube have background noise, and that was also how every 78 I've ever heard (handed down in my family, and others in other family collections I've heard) sounded like those youtube ones, and most people I know who remember them, remember them sounding like that also, with that kind of background "static".
And as for 20 plays ruining them, my guess is that many of them hit 20 plays in one day.
The background pops are caused by cross-scratches that are created when the needle gets deflected out of the groove by rough handling.
The hiss is caused by normal wear.
Both can actually be filtered out digitally these days.
It was pretty much standard practice to replace needles frequently. They weren’t expensive, and came in packages of 50 or 100.