"No one with a NAME, no one with a REPUTATION. "You can't be The Man unless you beat The Man". Fischer was The Man. Karpov didn't get to beat THE MAN. Karpov became THE MAN for Kasparov to beat. Kasparov beat THE MAN, the symbol of the Soviet Union, Ivan Drago of Rocky IV"
In that case Botvinnik didn't have anyone to fight against either. Kasparov was a Soviet citizen no less than Karpov.
"Karpov had no one to fight against"
Karpov was 1/2 of the most epic rivalry chess has seen, spanning five WCC matches and over 100 match games. All of them were incredibly close. One of the matches was drawn.
But yes, he didn't win the title by beating the previous champion.