Yes, pretty much only males will or would qualify for greatest ever at most sports. Welcome to earth. Sport by nature is usually defined by some uncommon aptitude in strength, agility, endurance, etc. The male animal almost universally has the edge on the female, with regard to those traits. I didn't write the rulebook, nature did. But this is not that discussion.
Why stop at gender, if we're going to rather arbitrarily split off into categories of greatest ever? Why not best blue-eyed cyclist ever? Best right-handed, male, brown-haired cyclist between five-feet-six-inches and five-feet-nine-inches ever? Best left-handed cyclist with nine toes wearing sunglasses between the hours 3pm and 4.25pm on October 12 2015, ever? I don't think naming Merckx the best cyclist ever is sexist at all. It's simply a fact. The word "cyclist" stands inclusive of both / "all" genders, species, handicaps, etc. He was consistently the best. Not the best "for his X." He was the best, out of everyone alive. He was better than any woman or circus dog or trained pig or bear who ever rode a pedal bicycle in competition. You have to start putting asterisks in if you're going to try to run him up against any girl's palmares or some bear on a unicycle who should be disqualified anyway for lacking a second wheel on his apparatus.
I think discussions like this should only concern road cycling. Sure, what about all the cx stuff and whatnot. That stuff is all niche genre. Would you figure in local crit races like red hook or mission into one's total palmares, too? Pretty soon strava results will be factored in and Phil Gaimon will be in the discussion for greatest ever. Or zwift, and some fat kid in ohio with a playstation or whatever gets a seat at the table. Let's keep it reasonable. If we're including cross-country races then why not bmx, freestyle, half-pipe, downhill mountain biking, that weird synchronised wheelie dancing thing they do on a basketball court to music? Where does it end? That stuff all happens on a bicycle too. But the discussion under present scrutiny concerns road cycle racing. Let's not get lost in the tall weeds here.
Schurter - first I follow cycling pretty closely and watch all the races I can. I'd never heard of him, so right off he doesn't deserve to be in any conversation over greatest ever. Now I see he's a mountain biker. Fine. Yes, dominant. I see, according to this article, that he raced a couple road races with Orica in 014. Why didn't he transition to road, then, where the money and exposure is much higher? He just preferred making less money, being less visible, as a mountain biker? Or was it because he wasn't good enough to race on the road with the pro peloton? Why didn't Orica, or somebody, offer him a huge contract to switch to road?
I don't know, the fact is mountain biking just doesn't have the variation in types of racing that road races do. So it's not as possible for a dominant mountain biker to display his talent across a wide range of races the way, say, a Merckx could by winning everything from one-day monuments to 21-day grand tours to the hour record, etc.