Obviously, we can't project how things would have gone in an alternate universe, but imagine a world in which Evert played all 4 Majors every year like players nowadays do. It is easy to see her having a dominant stretch like the ones you listed. Consider this stretch:
1976 French Open: DNP: Would have been the heavy favorite
1976 Wimbledon: Won
1976 U.S. Open: Won
1977 Australian Open January: DNP: Would have been the heavy favorite
1977 French Open: DNP: Would have been the heavy favorite
1977 Wimbledon: Lost in the SF
1977 U.S. Open: Won
1977 Australian Open December: DNP: Evonne Goolagong won
1978 French Open: DNP: Would have been the heavy favorite
It's easy to see Evert winning 7/9 of those Majors if she had played them, and it could have been 8/9 if she could have gotten past Goolagong in Australia. Extending this a few Majors:
1978 Wimbledon: Lost in the F
1978 U.S. Open: Won
1978 Australian Open: DNP: Would have been the heavy favorite
1978 French Open: DNP: Would have been the heavy favorite
Again, it's easy to see Evert winning 10/13 or 11/13 of these Majors. Would she have won all of these? Maybe and maybe not. We won't know because it was a different tennis world back then.
While on the surface your points have merit, you also have to factor in though the the Australian and French Open fields as they were were much weaker as well, for the reason their value was lower around then, the very reason Chris wasnt ever going to play them those years. Had they been higher value not only would Chris have played, but other top players would have all played, and this would have meant a stronger field, and more chance of her losing, especialy the Australian on grass (she won 2 Wimbledons out of 9 on grass from 72-80 when she barely played the Australian, so lets not pretend she would have just dominated a regular full playing field at the Australian).
For instance of the ones you mentioned had Goolagong, Wade, and everyone else played both 77 Australian Opens, winning 1 of 2 would be a reasonable estimate, despite that she lost Wimbledon that very year. 1978 Australian on grass she most likely loses to Martina. The 2 French Opens yes she likely wins. So that would still be 6 of 9 slams, which still doesnt compare to Graf winning 8 of 9, Martina winning 6 in a row, Court winning 8 of 9, Lenglen winning 12 of 13, Connolly winning 8 in a row, or even Serena at her peak winning 5 of 6 vs the deepest womens field ever (and since you introduced the what if discussion not only with Seles, but also with Chris, Serena would have been 8 of 9 had she been able to play the 2002 Australian Open, 2003 U.S Open, 2004 Australian Open, as I am sure you would concede she was the heavy favorite and likely winner of all 3 of those).
I am not putting Chris down, I am just pointing out it is a commonly accepted fact even by her supporting that in peak level play she is down the list of all time greats and GOAT candidates (still great by most top players standards of course). The strength of her career and why she ranks so high to many people was never peak level player, or greater dominance than other all time greats, but the amazing cummulation of her career through many years of incredibly high level, consistency, and longevity, and playing very well across all surfaces, even if only totally dominant on clay (although even on clay she took some brutal smackdowns from peak Martina, this despite that Chris is the clay GOAT, and Martina not even top 10 all time on the surface, which shows my point of peak play). In a fantasy event with all at their best NOBODY would pick Evert over Navratilova, Graf, or Serena for instance on anything but a clay court, and most would pick Court, Connolly, Lenglen, Wills, Seles at their best over her on those surfaces too (well minus Seles on grass of course), while others like Venus, King, Goolagong, Henin, Marble, would even be picked on their favorite surfaces over her if we are talking just peak level play and nothing else. So it would seem funny to me you rank Seles so high based purely on your view of her peak level play (which in her case is entirely subjective, and not stat based at all, as her best stats in her best years are far below those others I listed to, but given her unique situation I will give you a pass there although I totally disagree), then still view Evert so highly if you value peak level play that much. To each their own though. We obviously differ here so there is no point arguing further.
