. . . because, being inevitably based on intelligence estimates - read, “assumptions” - about Russian behavior, they would be laughed out of court by the judge before trial. No possibility of being proved beyond a reasonable doubt.
For one federal courts have no role in impeachment proceedings. The prosecutor is the House and the judge and jury is the Senate. One would hope that due process and reasonable doubt would win the day, but in our butt hurt political environment, power and animosity hold sway. I for one believe Trump to be innocent of collusion and obstruction, but I am sure there are enough uniparty members in Congress that would be happy to see the President gone.