[techsupporter]

I think it's two reasons:

1) People are becoming super averse to conflict and, by extension, confrontation. I think it's for myriad reasons. Not wanting to deal with the possibly-negative response; being accused of something; the other party exacting some form of retribution; and so on. I think the perception is that if one party says "[not-preferred reply]," the other party feels maligned instead of just that "it didn't work out."

2) Along the same lines, I think not saying "no" is also seen as responsibility shifting. "Well, I didn't tell them 'yes' so they'll figure it out soon enough." And then the ghosted party is then held as being responsible for their own feelings. "Not my problem you felt bad that [a possible employer | an acquaintance | some other interaction] never called you back. Those are your feelings, not [mine | ours]."