Because apparently not one single person on either side of the political divide is willing to speak the truth:
Yes, Trump and McConnell are letting Susan Collins and probably one other Republican Senator vote to hear witnesses. This is not, as everyone claims, to help them get re-elected in relatively moderate districts. Real (i.e. crooked) Republicans don't give a damn about Susan Collins, Lisa Murkowski or any other potential defector; if one does cross the party, they will be primaried by someone much more extreme than they are, and the result will just be an even more united Republican party.
What is actually going on here is a plan to see to it that the Democrats can't portray this as a party line vote, because two unneccessary Republicans were let to agree to witnesses.
It is all about the 2020 election, despite the fact that it will be consistently presented across the mainstream media exactly the way the Republicans want it- See, there are still Republican moderates, the Republican party is not 100% made up of fascist-enabling criminals, so it is perfectly respectable to go out in November and vote for them.
And the press will go to their graves pretending that this is an even-handed way to report on this issue.