People in the 19th Century didn't have anywhere near as many distractions as we do. Keeping focussed these days, requires a lot more discipline. Tolstoy wouldn't have to ignore phone calls, texts, emails, alerts or have the constant temptation of news updates, games, tv shows, films, music and about a billion other things, literally at his fingertips.
The other thing you need to consider, is that maybe EK has a life outside creating these games? You mentioned Kafka, who was a tortured individual with very low self-esteem. Writing was virtually the only thing that brought him any joy, and consequently he devoted virtually all his free time to it.