The problem wasn't about the conduct of the Biden's, it was Trump (allegedly) telling the Ukrainian President the Ukraine would only receive already allocated military aid if the Ukraine started investigating the Bidens, supposedly to get Joe Biden into at least political if not legal trouble that Trump could then capitalize on in a re-election bid. Whether or not the Biden's did anything wrong (and so far the have been cleared at least legally, tho I have to admit there is a stink of nepotism in my opinion) wasn't the issue, the problem was if Trump, the sitting president, abused the power of his office for personal gain by threatening to withhold public aid money allocated by congress.