Barrel life is usually limited by throat wear. How badly the throat wears depends on how much heat it is exposed to for how long. The steel damage is actually due to differential temperature expansion between the bore surface and the steel substrate. Every time it goes through a heating and cooling cycle, the surface steel fatigues and weakens. Eventually that leads to the alligator skin cracking pattern you see in a worn rifle throat. The surface attachment of the individual alligator squares to the substrate continues to weaken with further firing, and eventually it gets weak enough that a passing bullet cracks it loose and the propellant gas pushes it out of the muzzle. So it flakes off, leaving the throat uneven and resulting in poor accuracy.
In the 6.5-284, the case water capacity is 20% higher than in the 6.5×55, which gets normal high power barrel life. The slow powders used for the .284 case will sustain the heat longer, which multiplies the 20% energy addition still further.
The speed of the bullet does not directly determine the effect. The 16" battleship guns in WWII, firing at about 2500 ft/s, lasted about 400 rounds, IIRC. That's just .308 Winchester velocity, but they release a lot of heat energy. I suspect that because most well-known barrel burners are overbore rifles loaded to impressive velocities, that it leaves the mistaken impression that high velocity is required to burn barrels up.
Military "308" is supposed to be 2800 fps (usually not) and M118 is 2550 out of 7.62 chambers.
Add to that one how bad it is for people that love to rapid fire. On average a good USGI NM barrel was good for 7,000 rounds or more depending. I usually shot matches, but take it out and shoot a practical rifle match... it cuts the bore life. Moderate matchs like High Power weren't that abusive. Rattle battle... oh the pain! (and why ARs do so well these days).