That is not quite true. From 2009 to 2011 Gilbert was competitive in exactly the same races that Pogacar was competitive in today. In 2010 he was clearly 3rd best and in 2011 he plausibly could have won RVV. We also cannot give Pogacar any extra points because he is doing so as a GC rider as that is irrelevant (not saying you are doing this).
Generally I don't think you necessarily have to be the most versatile to be the best classics rider.
Your post also made the discrepancy between Pogacar and Evenepoel look larger than it was by listing all the races Pogacar competed in even though all of them apart from possibly SB and RVV were redundant because Evenepoel clearly could win them too.
Pogacar gets versatility points for SB (Evenepoel unproven on gravel) and when there are lots of cobbles (not like Evenepoel never rode on cobbles though).
On the other hand Evenepoel has won races on easy parcours that Pogacar would probably struggle more on (WC, NC this year).
You could give Pogacar MSR but Evenepoel could definitely ride that too and it's not easy to win for Pogacar either.
Overall I do agree that Pogacar is a better classics rider at this point because winning RVV does show impressive versatility and because Evenepoel could likely struggle to drop Pogacar on hilly races. Evenepoel does have his own bit of versatility on flatter, easier races that should deserve mention as well. If Evenepoel can show more of that I might end up favoring him in this regard.
Again, I said current peloton! We are not having a debate on who is best one day racer of all time or something. Pointless, it is Merckx. Nobody has gone into the GC-stuff at all either.
Evenepoel has never raced some of the races that Pog has won so far... you are basing your point on a hypothetical.
Pogacar has proved himself in every type of race... he is therefore the best one-day racer out there atm. There is no debate about that and I am not making the "discrepancy" larger than it is, if that is how you interpret that. That was just a run-down of the races he has won that features most there is when it comes to big one-day races.
I dont buy the versatility on a "flat" or "easier" course. What does that even mean? If anything, Pog has done long solos too. He was pretty spectacular on the last stage in Paris as well... if only he didnt have one JV-rider on his wheel.
Evenepoel has the chance to potentially take over the crown in the future... if he starts to race more of the biggest races and wins them. Like I said multiple times... we will see more in the future. I am not doubting that he wont or cant do it either. I dont think I have said that... I can only speak on the present and the past. Pogacar is the best one-day racer in moment of time, currently, backed by his results across every type of race and what races he has actually won so far.
Van Aert is one of few who comes close based on versatility... but he doesnt have the results (read wins) to claim being the best one-day racer. MVDP doesnt have the same versatility... but he has the big wins to back it up.
Only Remco could really be close to matching or surpass Pog, if he starts racing and making results in other type of races.