Yes, all true - but this is just the nature of the sport. Not all Slam titles are created equally. I'll be the first to admit that some of Roger's early titles were relatively easy, or at least compared to, say, his 2017 AO. Novak and Rafa also have their "easy Slams."
But me, the cake is taken by Johan Kriek, whose two Slams were both the AO at its weakest. 1981 was still a 64-player tournament. Kriek didn't even phase a top 10 player in either tournament, I believe, and beat Steve Denton--a guy who never made it into the top 10 at any point in his career--in both finals.
The worst Slam final player was undoubtedly John Marks, who lost to Guillermo Vilas in one of the two 1978 Australian Opens. But at least Marks defeated some good players to to get there, including an aged Arthur Ashe. But Marks' best ATP ranking was #60, and his best Elo was 1872, and his highest Elo rank #79.
According to Ultimate Tennis Statistics, here's a list of the easiest Grand Slam titles:
Easiest Grand Slam Title at Ultimate Tennis Statistics
www.ultimatetennisstatistics.com
Kriek's two AOs are 6th and 9th. Bill Bowrey's AO in 1968 was 1st, but that wasn't Open Era...so the Open Era easiest was the AO in 1972. Actually, the AO in 1968-70 the top 11 easiest. The lone absence was the 1969 AO...Laver had to beat Roy Emerson, Fred Stolle, Tony Roche, and Andres Gimeno.
Roger's easiest Slam, according to that page, was the 2006 AO (#20)..the one he faced Baghdatis in the final, and before him, Tommy Haas, Nikolay Davydenko, and Nicolas Kiefer in the 4R, QF, and SF. So some solid players, no true elite ones. Novak's easiest was the 2021 WImbledon (#30), where he beat Berrettini in the final, and before him Shapovalov, Fucsovics, and Garin, in reverse order. For Rafa, it is the 2017 US Open (#37), when he beat Kevin Anerson in the final, and before him, Del Potro, Rublev, and Dolgopolov.
Stan Wawrinka's three Slams are #1, #2, and #5
hardest, according to that metric. The Legend of Stanimal!