Monster Hunter World's PC debut has been rough, with poor optimisation the biggest complaint. To top things off, the game wouldn't even start on Intel and AMD CPUs made before 2012/2013, thanks to the use of a newer processor instruction in the title's DRM.
The problem has since been patched, but for a while there, if you tried to run the game on an AMD processor made prior to the Piledriver architecture (mid-2012) or an Intel chip before Haswell (mid-2013), it just wouldn't start.
The reason why is explained in this thread on ResetEra by user "Frox":
As the title says, the game's implementation of Denuvo requires FMA instructions to boot up and basically screwing a potential ton of users. MHW already launched on PC on China and there's ton of people reporting this problem.
Capcom posted about the issue on MHW Steam community hub, though it was light on details other than it being limited to "specific CPU or GPU model(s)".
At this stage, the company really needs to take a long, hard look at its PC porting strategy, because whatever approach it's using now is not working.