This is, of course, something of a matter of opinion.  There is no real way to objectively say that populism clearly helps Americans.  Instead, some people will say that it is helpful and others will say that it is harmful.

The main way to argue that populism helps America is to say that it allows the voices of the masses to be heard.  It is often the case that American society and American government come to be dominated by elites.  We see this in our Congress today, which is typically made up of rich people.  We see it in the degree to which they (arguably) do the bidding of the large companies, which are allowed to give huge sums of money to their campaigns.  What populism does is to give us something of an antidote to this feeling that the elites are in control.  When populist politicians come to prominence, it allows the “common people” to feel that their voices and their concerns are being heard at the highest levels.

In this way, we can say that populism helps to keep our society and political system stable because it lets more parts of our population feel that they are heard.