Before reading the article, I was thinking that many Triads tattoo women in their family with large dragon tattoos (I dated one of these girls when her family moved to Los Angeles). It was weirdly explained to me that if a man tried to hurt her and saw those tattoos he would be afraid of the Triad and leave her alone. I found the entire concept a bit repulsive, but it isn't my culture.
The article's claim that tattoos are associated with gangsters lines up with this.
The history of tattooing is vast, as with any subculture. There's a lot of history with bikers, gangs, tribes, artists, healers, etc. You should read about the history of Russian prison tattoos[1]. I'm biased because I am a tattooed person. All that being said tattooing isn't just for gangsters. Humans have a long history of marking their bodies permanently[2].
The article's claim that tattoos are associated with gangsters lines up with this.