True, but I think it would be fair to detract Kasparov from an equation with most GMs, Shirov included. GK played tournaments at the highest level for almost twenty years, and not the least, five extremely demanding matches against a very close to equal opponent, Karpov. Such a career is far more exhausting, mentally and physically, than a bundle of middle-of-the road tournaments without any expectations of your performances.

The swashbuckle / romantic era will always have it's appeal as we all love a beautiful attack. Tal's youthful flashy, amazingly creative, profoundly complex attacks are always a delight to play over, but he himself admitted they were often unsound, with jokes like "There are good moves, and then there are Tal moves."

His attacks were so effective because the complex tactics were difficult to solve over the board with clock ticking, and even if the attack came up a pawn short, the opponent would be near exhaustion and low on time and commit errors later on, which Tal could cash in for +1.

In the chess engine era many of those ideas get filtered out during home prep. Players are better prepared against surprises.

Then there's the other dynamic. Magnus commented that his playing style used to favor all out mating attacks and so forth, but when he switched up his approach he started winning more games.

In the case of those like Korchnoi.. his wife complained he labored relentlessly in his home prep [partly fueled by his determination to beat his arch nemesis Karpov] and even in his later years she thought he worked TOO hard, compromising his health.

And we have guys like Anand, forever remembered as a great champ in his prime, yet even now is still quite strong, but in post champion years his most valuable contribution is sponsoring, training, supporting the young Indian players. A shift of focus. A passing on of the torch, so to speak.