Why do antis automatically assume the worst in proshippers?

A mix of a rant and complaining over anti bs. Light TW for suicide mentions

A bit of context. I have a friend who generally leans more anti. I don't usually make friends solely on who likes my ships and who doesn't, so I usually don't care 99% of the time. I keep what I like private, unless it's some super popular mainstream ship, and we don't talk about ships. During the 1% of time we talk about ships, it's usually lighthearted and about how terrible certain discourse is going to be.

HOWEVER. Today, they received one of those anon asks just asking if they were ok with proshippers. Not even mention a specific ship. Their immediate response, was to screenshot it, send it into their close friends group chat, and make fun of them. All for asking over boundaries. They claimed the anon asked if it's ok they like shipping "kids and adults", then one message later, told them to kill themselves. Again, over an ask for boundaries.

Just. Why. Why do they automatically assume proshipping means darkshipping? Why is their first instinct seeing the word proship that they're all terrible person and ship every problematic trope and dynamic under the sun? Why do they automatically think it's ok to tell someone to kill themselves over ships? Just... aaaaaaaaaaaaaaaaaaa whyyyyyyyyyy