When Co-workers do things like ask about weekend plans, chat about non-work topics, eat lunch in the same room, they are–subconsciously–reaffirming that they are part of a cooperative (or, minimally, non-antagonistic) social group.
The other primates cement social bonds by grooming each other; we do it by making small talk.
If they solicit your participation in these rituals, and you repeatedly refuse those bids, you are marking yourself out as, at best, an outsider to the group, and thus potentially antagonistic.
This is all happening on the monkey-brain level; they have no idea what they’re doing or how they are interpreting your response, so there’s no way to clear up the misunderstanding.
To the ape sleeping in your co-worker’s DNA, either you are part of the grooming circle, or you are an outsider who, for all it knows, may be coming to steal all the bananas.
Even if you would prefer not to socialize with your co-workers, it’s generally worth it to set aside 5 minutes a couple times a week for phatic communication. You don’t have to answer your co-workers’ affiliative signals every time, but it’s less trouble in the long run if you respond to a few of them.
on the one hand this is, as far as i can tell from my own experience, 100% true
on the other hand i fucking hate it, because “coworkers have toxic prejudices determined by monkey brain instincts that they are incapable of ever learning to control” is somewhere on the level of “men are always gonna be abusive creeps, their brains are just wired like that,” except it’s 1. actually true and 2. true about the vast majority of humans. Apparently.
…still holding out a small hope though.
(this brought to you by a long, LONG week of ALWAYS being the one who had to stop whatever work I was doing and get the phone or the customer at the front desk, instead of my coworkers, because they were busy with totally un-interruptable things, like talking about their kids or their in-laws or their vacations.)
(and yeah. maybe this is a thing that they could have avoided by just not crossing a boundary of excess, and not getting so deep into a conversation that they couldn’t notice an important event before the person doing actual work noticed it and had to get up to deal with it.
But. Please let me know when you find a workplace where people are actually capable of starting a non-work-related conversation and NOT crossing that boundary of excess. I still have no proof that such a thing ever happens.)