My model: I think quality attention is a finite resource, and that many people have a ravenous appetite for attention. The people around them are not under any obligation to do the emotional labor to give them their fill. Expressing a desire for attention (or anything your interlocutor could give you), overtly or covertly, easily comes off as a manipulative indirect request/demand. This is why people find attention-seeking so gross. Because attention-seeking is agreed upon as a contemptible behavior, people use this as a weapon against each other and accuse others to throw everyone else off the scent of their own vulnerability.