Zoro didn't have proper rivals. Instead of ZKK, they could have wished for strong samurai. Kyoshiro had a potential. No one interested in WSS. Not even closest swordsman Law. So Zoro journey is just shallow without any setbacks. You people can think Oda dickrode Luffy too much, but he is the one who was given many set backs, weakness to his powers than anyone else. Tje constant doubt whether he won or lost is the prime example.