Some people assume everything said online is others' entire personality

It's wild when people comment under others' posts saying (insert insults here) about OP and assume that the post is OP's entire personality or that everything OP writes is repeated aloud. The post could be about little things their partner does that irks them, things OP finds unattractive, or vents about work. I see the negative assumption comments everywhere over the most mundane posts.

For example, I came across a post where OP vented about a problematic client and many comments were along the lines of "It's your job, so why are you having difficulty with this? You sound like an unprofessional asshole. Shouldn't you know the answer to 'why are people this way'?" Whereas I read the post as someone venting about work being tiring and asking a rhetorical question, not actually openly admitting to hundreds of people about being incompetent at her own job and being clueless toward basic human behavior.

There was another short post about OP venting about things his partner does that irks him like not folding laundry. Some of the comments said "I couldn't imagine having a partner who gets this angry over laundry" or "Your partner is probably sick of hearing all your rants about her." I was thinking he wanted to vent into the void of the internet but still loves his partner because they sounded like little pet peeves everyone has of their partner. I mean, it's possible that he voices every single complaint and thought to everyone and has voiced everything he's typed, but ya know, that's not my first guess.

Are these people assuming posts about itchy rashes are being shared to everyone in person too?