They did in Australia. The unfortunate circumstance being the definition of a gang meant anyone affiliated or sharing colours that could be contributed to a 'group' when in the vicinity of one and other could be convicted.
Wether intended or coincidental (e.g. you go to the Pub wearing the colours of a Union or Football Club and by co-incidence, 2 others are in the same premise of the same affiliation. The definition of a gang is 3+ persons wearing 'affiliated colours'.
I would suggest that blatantly strawmaning someone only worsens your position (and breaks one of the HN guidelines).
They weren't "defending violent gangs" in any way, they were providing a practical example where laws were passed to try to do what you said and they obviously didn't work as expected (nor did they solve the problem).
Maybe providing another example (or proposal) would be a better way to discuss your position.