Back when Civics was taught in 8th Grade, most Americans understood the extent and limits of Congressional power. You apparently weren't paying attention, or came along after Civics ceased to be taught in government schools.
Congress, of which Rep. Gowdy is a member, has the power to subpoena and investigate in its Constitutional oversight of the Executive branch. However, the Constitution does not allow Congress to indict or try anyone for crimes (except for impeachment of the president or federal judges); that power is invested in the Executive branch through the Department of Justice.
President Trump has been in office for less than a year, and Attorney General Sessions for ten months, and they have had to combat obstruction at every turn. These are smart men who knew the score before the election and knew exactly what they needed to do. They are busy and their enemies are terrified; for now, that's all we need to know.
From what I’ve read Sessions’ DOJ has done quite a bit of obstructing. Congress has been asking for docs. and Sessions has produced nada.
Thanks for your insult that I do not know about government.
Halderman, Erlichman, Dean, Mitchell and others went to prison for Watergate.
I listened to those committee hearings religiously. This is far more serious than Watergate.