Very much this, and the realisation that attention is finite and very highly rivalrous is one that needs a great deal of amplification.

I'm finding Herbert Simon and Alvin Toffler's Future Shock to be pretty fascinating reading in this context, both from the early 1970s. Toffler cites significant earlier work.

I'm also starting to wonder what the long-term effects of high-level information overload are. Toffler's giving me considerable pause on that account.