Many rush to blame Antifa, white supremacists for unrest, but few offer evidence

I also searched news stories. There were a lot of stories repeating the claims, but without hard evidence. There are some later that noticed there is not much evidence--

Many rush to blame antifa, white supremacists for George Floyd unrest, but few offer evidence to back claims - Chicago Tribune 

The mayor and police commissioner have attributed some of the violence during the protests to unidentified groups from outside the city and state, but there did not seem to be evidence of that overnight.

- Looters Strike at Macy’s and Midtown Manhattan During Protests - The New York Times

The extremists taking part in riots across the US: What we do and don't know - CNNPolitics

https://www.cnn.com/2020/05/31/politics/outside-influence-extremists-riots-us/index.html

(CNN) — Law enforcement and federal officials say outside elements from both far-right and far-left groups are helping fuel the violent and damaging confrontations that have marred protests across the country in recent days, despite President Donald Trump's focus just on Antifa and the far left.

Although interference in this way may be happening, federal and local officials have yet to provide evidence to the public.

Videos, threats, but few signs protests have been stoked by white supremacists or extremists ...  NBC

I think people are blaming small groups because they don't want to face the hard facts. First, they are mostly blaming "someone else"--the left blaming far right, right blaming far left.

And if the rioting is caused by a large group, then they have to admit that a large group is committing violence either 1) with justified anger or 2) without justification, out of selfishness. Either is scary.