Not so much from the accumulation of knowledge because players can only study so many games. The difference is largely because their are more people today, they have more free time, and they could play vs high level opponents sooner.

Remember people reach peak play in ~15 years, but they don't nessisarily keep up with advances.

PS: You see this across a huge range of fields from running, figure skating, to music people simply spend more time and resources getting better.