The results aren't as dominating as everyone wants to believe. They were pretty fortunate in 2015 to face a Cavs team without two all stars. They lost in 2016. In 2018, they were taken to the brink by Houston and if that had been a Finals series, it would have gone down as one of the best Finals ever. Instead people just remember that they swept a pretty weak Cavs team.
They were truly dominant during the 2017 playoff run. That team was the best I have ever seen and probably had a lot to do with Kyree leaving. However, they have been beatable in every other playoff run. They have the best group of four players in the NBA, but after that, its not that good and they are definitely beatable again this year.