Why do so many Link monsters specifically require effect monsters as materials?

S.P. Little Knight, Accesscode Talker, Underworld Goddess, Borrelsword, Zealantis, Verte Anaconda, etc. Is there any particular balance reason I'm not thinking of that you can't use normal monsters to summon them? Typically, normal monster decks are weaker, so what is the logic behind making it more difficult for them to access so many generic link monsters? If Konami wants to prevent using tokens, they can just add a "no tokens" clause to the materials, like Apollousa or Relinquished Anima. What am I missing here?