That’s the counter argument. And a pretty good one, but at the same time you can see the problems that would occur if you allowed the President to be indicted without first being impeached. The Democrats have a long history of using criminal charges for political purposes. A lone prosecutor could bring the entire government down even if the Congress refused to impeach.
Whether I can see a problem or not is not the issue. The issue is what the constitution and federal law says. I still have seen no evidence whatsoever of any suggestion that it is impossible to prosecute a sitting president without impeachment. I have heard a lot of blathering by talking heads who want to protect people like Hillary Clinton, but again, no evidence whatsoever.