The way I see it is the majority in the house abrogated their responsibility.
The House conducted a House investigation to determine if there were grounds for impeachment. They concluded there were, and they drew up articles of impeachment.
The next step is the actual impeachment trial, where the Senate has the authority to compel witnesses to testify under oath under threat of contempt. The House lacks this power over the other branches of government (i.e. as White House counsel explained, they would not comply with any members of the White House staff being called before House committees).
But since the Senate chose to call no witnesses, no witnesses were compelled to testify under oath in an impeachment trial.
There's a reason Congress has the approval of only 1 in 4 Americans polled.
Not as exactly clear-cut as this time around.
1. https://en.wikipedia.org/wiki/Impeachment_of_Bill_Clinton#:~....