Undoubtedly hinder policing.
However, when you see complete lawlessness and images of police either unable to cope or unwilling to do anything other than move the scrotes on so they can loot somewhere else, then it is quite easy to understand why such groups might form.
It is possibly the most worrying thing. When the public lose confidence in the police (and I am talking about their ability to immediately protect, not solve crimes or prioritise targets) then you have a real problem.
It is even more apparent when you realise that the scrotes 'rioted' for exactly the same reason. They knew the police could not stop them or deliberately wouldn't do anything.