Middlemen
"This boils down to the fact that someone, somewhere, is willing to pay more for these services than they cost to provide. This is the very definition of adding value."
By that logic, manufacturers are adding value as someone, somewhere is willing to pay more for their services than they cost to provide. They, along with distributors, are not the only ones (e.g. support services) by any stretch of the imagination - however that is sufficient to disprove the assertion
"IT distributors: The only people adding value to the world economy"
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"Unless you'd all like to tell me why it is that distributors add value to you?"
They don't in general.