Duh
the real thing to point out is no one else is even close to the #2 HW GOAT Nogueira
Cro Cop
Barnett
Werdum
Sergei
Sylvia
Herringx3
Hendo
Rodriguez
Coleman
Semmy
Valentijin
Tamura
Schaub
He beat peak Bob Sapp (obviously not a ranked fighter, but out-weighed by 145-lbs, was pure roids/power/strength, one of the most physically intimidating humans on the planet if not the most against skill/heart, one of MMAs most important wins - Sapp hadnt lost yet and stopped Ernesto Hoost in K1 one of the GOAT kickboxers twice that same year)
By the time he won the UFC title he was 31-4-1-1
2 of those losses and 1 NC to the GOAT Fedor.
Other 2 a split decision narrow one to Barnett in the gureatest HW fight of alltime, even till this day. One of the GOAT MMA fights in general. He avenged decisively
other loss a well known robbery against Hendo he avenged decisively and finished him. Nog was the P4P best in the world pre Fedor and remained as either the #1, 2 or 3 HW in the world from 2001-2008. Vast majority of the time as 1/2 (2 post Fedor, 1 pre Fedor), and a small time as #3 after Barnett fight which he avenged and reclaimed. He was also perenially in the Top 10 P4P (mostly in the 4-8 range in that span from 01-08 peaking at #1.
Fedor and Nog have a combined 60-2-1 record excluding fights VS each other to start their careers. These 2 are near untouchable and we havent seen HWs close to their peak selves yet. Fedors 2 demolitions of a peak Nog are perhaps the biggest reason hes seen as the GOAT considering they are 2 of MMAs gureatest wins