I thought so too in the beginning. I have been playing for six months and have made it to Legend, level 93 with a 68ish average so I can see how years of play would elevate some players and enable them to shoot extremely low scores. These guys have also mapped every club and use various spreadsheets on wind and green break (counting dots). I havce played a few of these good golfers in situations that are timed and they are good but don't typically shoot scores that low due to time limits. When playing tournaments, they usually have unlimited time to figure calculations on each shot.
In my case, I am retired and have some health issues so I spend about 12 hours a day playing and spend around 150 dollars a month on quality balls. In short, it takes a lot of practice and money so I can see how some might achieve these scores.
That said, I just played a level 39 Pro in a nine hole match on Chambers bay in 25-30mph winds. He was one under through 6 holes. When I asked what his other profile looked like, he played dumb and eventually forfeited with a one shot lead. Cheater or not....I think so.