Why has it occurred to seemingly no one that asking for an investigation of an opponent could help the opponent? If the investigation concludes nothing happened and the opponent did great things, then why is this a problem?
The opponent may come out of that investigation looking far better. Not far worse. Asking for an investigation is a 50/50 thing.
I think your 50/50 proposition is born out by the fact that the heavily investigated Trump has come out clean. The Democrats who frequently indulge in corrupt acts can’t believe there isn’t some crime that Trump has committed. So, they press on with each new false allegation.
Meanwhile, investigation of the plainly visible corrupt act of extortion that Biden boasted about must never be allowed. Democrats believe that their long tradition of corruption has established a sort of “easement” that can never be challenged. To do constitutes an impeachable offense. The media backs them up on this. Impeachment is needed to restore the prior regime of unexamined Democrat abuse of their political positions.
There is a difference between a witch hunt and an investigation.
Lots of people wrongly convicted of crimes can vouch for that.