They absolutely deserve the blame, but the point is that these people have always existed, and probably in much larger numbers than we’d like to believe.
A lot of people seemingly believe that the UK went from a country that loves all immigrants to a hate-filled country in just over a decade of Tory rule, but all that has happened is the government and the media have informed the public that extreme views are welcome in society.
IMO what needs to happen is a swift push from the government to say “no, violent protest will result in prison” AND actually fucking stopping them. The police know ahead of time where people are protesting, and the second so much as a can is thrown at a building the police should be making arrests - hundreds of them. Doing anything else sends a message that peaceful protest results in jail time, whereas torching an immigration law firm or hotel is fine.