I think kpop artists spend more time building an emotional connection with their fans. In Korea kpop stars are on TV a lot, usually doing things like playing games together, sharing stories, hanging out at home, at work, at a cafe or restaurant. It makes you feel like you know them personally. With social media there are more people doing things like this, and those people have similarly devoted fans (e.g. the Kardashians). In the west artists still expect and want some degree is privacy, they want to make music but don't necessarily want to be a "professional famous person". My understanding is that for a kpop artist that's basically part of the contract.
As someone who enjoys both kpop and western pop I feel there's definitely something that about kpop that creates a more intense fandom, but it's not easy to put one's finger on why exactly. One reason might be that in the western music industry there's more of an assumption that the product is the music whereas in kpop the artist is the product. Kpop artists put out a lot of material that makes you feel close to them and makes them relatable. I'd say that the culture of Korean media is more intimate in general. Kpop stars appear on a lot of tv shows where they just play games, share stories, spend time with at their home, work, coffee shop, restaurant. If you have a favorite western pop star you might see them on a talk show or read their Twitter feed, but it doesn't really feel like you're spending personal time with them week after week.
If there are multiple recipients then they may need to each maintain their own queues. But these queues may implicitly have an expectation of being in sync with each other. If you use a centralized message queue then there will be a single source of truth about what messages were received and in what order. This can help to avoid or debug problems that can arise if sender fails to send request to some receivers or if some receivers fail to process requests.