Yes, exactly. Russell has shown high potential in the past, and he's now had one end-of-season race in a Mercedes with absolutely zero pressure on him. He was expected to finish behind Bottas. He was a good young driver temporarily filling a gap for one race. He drove very well, and he outperformed the limited expectations.

This is very different to the pressure on Hamilton, fighting for the title, expected always to be at the front, expected to never make a mistake. And Hamilton has proven himself year after year after year, in the dry, in the wet, imperious and often faultless, and overriding poor team decisions that would cost other drivers victory.
Yes, Russell shows promise, and his performance vs Bottas was good, but it also highlights how poor Bottas was. The idea that he can be expected to just slot into Hamilton's role and perform the same as Hamilton over the course of a season is absurd. He may perform well, he may not. The point I'm making is that one good race with zero pressure doesn't immediately transform a talented youngster into a 7-times champion.

Imagine if it was Bottas instead of Hamilton who missed the race, and Russell teamed up with Hamilton. Does anyone seriously think Russell would have been challenging for the win?