That entirely depends on how if Merckx were riding today he would be on a modern bike, with modern performance science, nutrition, strategic planning, etc. If his numbers would be superior, his will to win the same, then perhaps he could beat the best today. Conversely, how would Tadej or Jonas be in the conditions of the late 60s-early-70s, racing on steel frames, 170 days a year, on poor nutrition, etc? Would they beat Merckx or De Vlaeminck? This is why any real comparison between eras is impossible. It's like the Messi-Pele/Maradona debate. The game of football was played so differently between their eras and it's the same in cycling. As for the competition., Merckx faced the best cyclists in the sport at the time, during an age when riding a bike to get around was comonplace, much more than today, in continental Europe. In Italy there was even a game of plastic balls with cyclists pictures on them, which could be traded much lake baseball cards at the time in the US. That sort of thing doesn't exist anymore, while fewer ride bikes to get around and so the popular level of the sport has diminished and with it the viable number of talented riders to fill the pro ranks. Today that is made up for by the more global arena from which the pro ranks fill their teams. But to say Merckx only competed against cyclists from three other nations is misleading. All we can say is that Pogacar races in conditions that maximize his sensational physiological parameters, allowing him to reach performance levels that rival any of those of the past, for which some consider him the goat. The incredible thing about Merckx, however, was that, despite sub-optimal scientific preparation and racing so much year in and year out during his career, he still managed to win just about all the major classics and GTs multiple times. Impressive.It is simple