@teruru
Most people in Japan are used to slurping, and it’s usually a sign that you love the food. But to foreigners and locals with sensitive tongues, it’s considered rude. Thus it’s called “harrassment.”
In the case of those with sensitive tongues, the best analogy I can think of is “eating a block of cheese in front of someone who’s lactose intolerant” since people with sensitive tongues can’t slurp or scarf down a bowl of ramen.