Why is each hokage weaker than the last (other than Naruto)?

Did the Konoha lower their standards every year? Cuz Hashirama and Tobirama are strong as hell (with Tobirama being weaker than Hashirama), and Hiruzen trained the 3 saanin (but he's still weaker than Tobirama)

And I mean....does Minato need any introduction?

Like what are Tsunade and Kakashi doing in this situation? Cuz they sure as hell ain't doing this

And Shikamaru is acting hokage rn and he's even weaker than Kakashi

Naruto is the MC so it makes sense why hes strong as hell, but why is each hokage weaker than the last?