I have no problems with people pointing out the hypothetical what if of if Evert and Navratilova played more Australian and French Opens. The problem though, particularly regarding Navratilova, is what many Navratilova fans either dont recognize or fail to acknowledge, is this would hypothetically give Evert many more probable slam wins than Navratilova. Think about it, with everyone playing the French in the 70s, Evert almost certainly wins 76, 77, and 78, with only an outside shot of say Goolagong stopping her one of those years. No way on gods green earth Navratilova wins RG any of those years, even if Evert loses any of those years Goolagong or an aging Richey or either the ones to do it or win it instead. Navratilova wasnt even contending on clay on tour yet, she only reached the RG final in 75 since nobody (besides Evert and Martina) played. Heck even if Navratilova played the super depleted French Opens that existed I am not sure if she beats Barker, Ruzica, Jausovec, the 3 winners, and the rest of the field, to win any of those years. Maybe she wins 1 of those 3 then, I would say that is a best case scenario.
Then at the Australian Open, well based on her Wimbledon results it is safe to say Martina isnt winning in any of 74-January 77 versions. And even in the fields that were present in their depleted state she probably never beats Goolagong, a better player at the time, who dominated the event from 74-77. She didnt even make a Wimbledon final, and she was much better at Wimbledon than the Australian in her prime. She has 3 potential shots of ones she missed, late 77, 78, 79. Assuming a full field she probably wins 1 of the 3, she wasnt even dominant at Wimbledon yet despite winning 2 of the 4 from 77-80, let alone on tour. In the depleted field that existed she probably wins both 78 and 79, and loses to Goolagong in 77. By contrast Evert would have a good shot against Goolagong even on grass by 76-77, when she was starting to really own the match up. And the early 77 version was won by Melville with Goolagong out due to pregnancy. Evert probably wins atleast 2 of the 3, maybe losing to Goolagong in 1 of her 2 wins. 78-80 I would guesstimate 1 of 3, similar to the odds I am giving Navratilova in the 77-79 period. That is assuming a full field.
Evert would have roughly 24 slams and Navratilova only roughly 19. Evert would now almost certainly rank higher than Navratilova all time on almost everyones list. I know many rank Court behind Navratilova, but that is a totally different situation. A non popular non U.S player, who has the stigma of the then lesser regarded Australian Open and a huge proportion of her titles coming there. Navratilova's exact contemporary of almost the same age with 5 more slams than her, Evert would clearly be ranked above Navratilova on almost every list.
So if you are going to get into what ifs about the Australian and French Opens in this period, you can not ignore this element, and it probably ultimately hurts Navratilova more than it helps her. It does not help her much, or any, in a comparision with Graf and Serena, and likely just lifts Evert further above her and in fact makes Evert the potential GOAT now and Martina a fairly distant #2 in her own time, rather than the perceived #1 in her own time slightly over Evert as she is seen now. In fact it might make it more clear Court now belongs her too, as even with playing the so called weaker slams Navratilova is now still probably far behind Court in total slams, so much so the perception might be now Court would still be ahead even with stronger Australian Open fields in her day.
Not surprisingly suppporters of MN consistently ignore this reality, either through ignorance, (more likely) desire to not acknowledge this inconvient truth, or convenient cherry picking. And if that is going to be the case, there is no point into even getting into the Australian and French Open what if scenarios at all, atleast while MN is concerned. As already noted, even when forgetting Evert, it doesnt even help Martina much in the first place, as she did not excel much in the 70s, was a nothing on clay in the 70s, and does not even in a probable breakdown benefit much anyhow. Now Evert supporters, it is different, they do have a very valid case to lift her up through this argument, without being inconsistent.