I feel like it used to be (I'm thinking 1990s or so) the norm that basically everyone reclined starting from the first in-flight announcement, except for mealtimes. Come to think of it, didn't those announcements from the pilot often specifically invite passengers to recline?

I am curious why, and when exactly, sentiments around this apparently changed so much. Was it tighter row pitches that prompted the shift? Widespread ownership and use of laptops?