It's easier in this world to assign blame (or credit) monotonically of course. Something bad happens, it's the fault of "X". The fact is, a bad thing usually is the fault of many, or even no one. But "we" like simply fault assignments. My team lost because of "X". It simplifies life, it's too hard to mention A, B, C, D, ..., so it's just focusing on "X".
And of course, when some politician is reviled, it's standard to assign fault to him or her uniquely and ignore anything else that may complicate that picture. Why are we seeing inflation? It's the fault of Biden, or Trump, or Pelosi, take your pick depending on how you lean. Why did Russia attack Ukraine? Biden's fault, or Trump's, etc.