You’ve given yourself the answer. Whenever anything becomes easy to steal, people have, and always will, take advantage of that. This isn’t some new occurrence. Humans have always been this way.
I think the “socially acceptable” part is just rationalizing that SO MANY people are doing it, as noted in the article, that people shrug and go along with the crowd.
You are just being exposed to people’s rationalizations for the first time, but people and stealing have always been this way.
So, I’m curious what do you think about libraries stealing customers from authors?