Can I also say it's easier to win a WC as a belgian than as a Slovenian or Slovakian? Can I rate Sagan's wins higher than Merckx?
No idea. Haven't dug that deep into how the belgians raced as a unit during Merckx days. In cyclocross it's almost every man for himself. I also don't know enough about Sagan behind the scenes team. Certain countries are also expected to carry the race thus weakening them. I also believe that most of the time (75% - a number i pulled out of my hat) the strongest/most suited to the race wins.
All in all though, I would argue that in some cases it would def. be harder for riders of certain countries to win the WC, thus making it a more difficult/bigger achievement. Logistics, help during the race, ... .
I can say that WVA was a perfect foil for Remco during the Olympics, and was a perfect guard to quiet/shadow MVDP. Mvdp did not have that kind of rider. Pogacar has some solid riders like Tratnik and Roglic as a foil. But they (Roglic and Pogacar) don't work well together. So team dynamics can be harder. When Pogacar won WC, i think Tratnik (or some other slovenian) did a great job, and Pogacar was dominant. When Remco won his WC, it was also more his doing imo, than it was during the olympics. And what i mean by that is, that if you take WVA away, maybe MVDP wins Olympics. But i think Remco would have won in Wollongang regardless of wva/team belgium presence.
The Dutch woman have been famous for refusing to work together, thus sabotaging each other. So strenght can be a backstabbing sword. But like I said, all in all i do believe in the premise that certain riders of certain countries are up against a bigger wall. making the achievement bigger.
Biniam Girmay race achievements pale in comparison to others. Bit i have no doubt that for many millions he'll go down as a bigger legend in comparison to others with the same level of, or even greater palmares cause of being a trailblazer. Having a more difficult path.