Distillation
Sometimes people don't have a chance to read a book but get access to a detailed summary of it. One shouldn't chalk that up to intellectual laziness. Accessibility can be an issue — still is. I came across an anecdote about how one Rudolf Carnap was able to get his mind around the literally massive Principa Mathematica even though he couldn't get access to it. This came from a not so ordinary summary. Here's an account from David Embods & John Eidinow's Wittgenstein's Poker:
Carnap, when he was an impecunious graduate student in Germany during the hyperinflation of the early 1920s, had written to Russell to request a copy of this 1,929 page, three-volume tome, which was unavailable — or unaffordable — and Russell had responded with a thirty-five-page letter detailing all its main proofs.
A thirty-five-page letter is massive to our standards (at least mine). When compared to a 1,929 page book, Russell had actually done Carnap quite a service — a distillation of the Principa Mathematica from one of the authors. Carnap took the proofs from that letter into the philosophical meetings with the Vienna Circle who looked to Russell as one of their touchstones. Who's to say whether the thirty-five-page letter from Russell had a role in that?
Distillations of ideas are as important as ever. Nobody will read every book in the world, let alone every blog post, but we can get a sampling of them from those who have, a lens into what people find insightful. Is that not one of the purposes of a personal blog?