You might be surprised how little of the "sticker bandwidth" on a residential connection you can actually use when you are sending UDP at a highish packet rate,

You might be surprised how little of the "sticker bandwidth" on a residential connection you can actually use when you are sending UDP at a highish packet rate, perhaps to an international destination, and need low loss+latency+jitter. The average experience of users would go down significantly as you start to multiply the bandwidth requirements, which is why P2P isn't typically used for more than 2 participants despite the potential bandwidth savings to the operator.