I'd strongly disagree with that. I mean, before Bayonetta was added to Smash, I don't think people would include Bayonetta as significant enough, yet here she is. The problem is also not just what isn't there, but what is - a fair few characters are variants of another, either conceptually or mechanically. The list of female characters who are
1. Exclusively female
2. Non-derivative mechanically or conceptually (ie, no ZSS)
1. Samus
2. Peach
3. Zelda
4. Palutena
5. Bayonetta
6. Rosalina & Luma
Comparatively, derivative female characters, or female characters with a male option (either default or not)
1. Sheik
2. Ice Climbers
3. Zero Suit Samus
4. Wii Fit Trainer
5. Inkling
6. Isabelle
7. Dark Samus
8. Daisy
9. Corrin
10. Robin
11. Mii Gunner
12. Mii Brawler
13. Mii Swordfighter
14. Villager
15. Bowser Jr. (as Wendy)
16. Pokemon Trainer
17. Pikachu (as Pikachu Libre)
18. Pichu (as Spiked-Ear Pichu)
19. Lucina
Pardon if I missed some. Comparatively, when the standard is applied to men...
1. Mario
2. Bowser
3. Bowser Jr.
4. Donkey Kong
5. Diddy Kong
6. King K. Rool
7. Wario
8. Yoshi
9. Pikachu
10. Link
11. Meta Knight
12. King Dedede
13. Ridley
14. Marth
15. Ike
16. Shulk
17. Ness
18. Fox
19. Pit
20. Captain Falcon
21. Pikmin & Olimar
22. Little Mac
23. Mr. Game & Watch
24. R.O.B.
25. Snake
26. Sonic
27. Mega Man
28. Pac-Man
29. Ryu
30. Cloud
31. Simon
32. Joker
And derivative...
1. Luigi
2. Dr. Mario
3. Ganondorf
4. Young Link
5. Toon Link
6. Roy
7. Chrom
8. Inkling
9. Corrin
10. Robin
11. Villager
12. Wii Fit Trainer
13. Ice Climbers
14. Falco
15. Wolf
16. Lucas
17. Ken
18. Richter
19. Dark Pit
20. Bowser Jr.
21. Pokemon Trainer
22. Mii Gunner
23. Mii Swordfighter
24. Mii Brawler
More than 3/4 of female characters are either:
1. Semi-clones/Clones/Echo Fighters
2. The same person
3. Secondary gender options
4. Default gender options
Whereas less than half of male characters fit one or more of these qualifiers. When I see that, it's just hard not to perceive a bit of a bias. While there is undeniably an issue with representation of women outside of Smash influencing this, it's not so bad as to justify this big a disparity.