This is also largely due to technology. Less about sport-specific technology, and more about technology in general.

The biggest reason why top-level standards in sport have risen over the past few decades in disciplines as diverse as distance running to powerlifting to ski jumping has less to do with improved training for top end athletes, and more to do with the increased standard of living for the world's population. You can't have Kenyans dominating every marathon if they are all starving in famines with no knowledge of the outside world. You can't become a world champion swimmer if there are no swimming pools. And you can't get on the figure skating national team if you have to help with farm chores every morning instead of going to the ice rink to practice. Essentially, we have opened the door to those people who are simply preternaturally good at their sport to become top-end athletes. Someone is simply a genetic freak who was designed to dominate at curling, but they might be living in a rural villiage in Pakistan. Drop an ice rink (that gives out free lunches and plays curling highlight reels on the jumbotron) in that villiage, and Muhammad will soon be the talk of every bar in Canada.

As an average person, advances in sports science are more likely to get you lost in the sauce than push your performance to elite levels. Often, a 20 page training pamphlet from the 1950s is the best training advice someone can get, because it tells them the fundamentals of improving at their sport, rather than getting lost in the minutiae.

The big scientific improvements that have raised the standards in sports are things like:

• Improvements in sport-specific equipment, like tennis raquets.
• Anabolic steroids.
• The psycho-social effect of a new standard being set (see: the 4 minute mile).
• The invenion of new, superior techniques for performing the sport (see: the Fosbury Flop in the high jump)
• The invention of high-intensity, sport specific training modalities (eg, futsal for soccer).
• The invention of convenient salty sugar water for long, hot, hard training sessions.
• Acceptance of reasonable amounts, of strength training as a base-building performance enhancer.
• Acceptance of reasonable amounts, of steady state cardio as a base-building performance enhancer.

Everything else was either already known to the athletes of decades past, or else is a marginal performance boost that elite athletes are experimenting with to get an edge on their opponents. Things like supplement stacks, nutrient timing, planning mesocycles, or performance hypnosis techniques are, at best, marginal improvements. They are popular among elite athletes because elite athletes are already maxing out at the fundamentals of their sport and are looking for any edge they can get. And they are popular and talked about among the lay population because it is easier and more interesting than focusing on the fundamentals. Eg, the 37 year old tennis player who wants to improve their game who starts periodizing their tennis training and tracking their macros, rather than simply accepting that they need to make more time in their schedule and widen their social circle so they can play more tennis with people who are just at or above their current skil level.

Yes, like the racquet technology isn’t going to help Joe Sixpack weekend warrior. It takes all that training to be able to fully utilize the technology. The racquet size increase has led to so much more consistency with striking the ball that rallies last way longer now. Longer rallies require way more conditioning to survive!

Yes. The application of scientific rigor to all aspects of sport have produced better human outputs on orders of magnitude and equipment is so much better that it is incomparable to that of a half century ago, across almost all sports — from shoe technology, to golf club design, to skates and sticks, to gloves and even the ball.

Most all sports have seen a revolution in skill and performance level since the 90s. Even is sports like soccer, which is much less dependent on equipment, the change sports science and applied biology have led to in training and recovery cannot be overstated.

most world records have been set in the past couple of decades

Afaik this was true a few decades ago too