Well, then they have to advertise the bandwidth that they can actually guarantee for 99%?! What is the justification for advertising speeds that you can expect

Well, then they have to advertise the bandwidth that they can actually guarantee for 99%?! What is the justification for advertising speeds that you can expect to not actually achieve? I mean, yes, it's obvious that overselling is in the interest of customers, and as such customers should accept that under more or less exceptional circumstances the service does not reach the advertised performance, so you maybe shouldn't use it for stuff that reacts catastrophically when bandwidth requirements aren't being met, fine. But how is it anything but deception to advertise bandwidth that the user can as a matter of fact not expect to be available under normal circumstances? For comparison, take electricity: My connection to the grid might be built to be able to supply 40 kW, say. Now, if everyone were to actually pull 40 kW from their connection at the same time, that absolutely would not work--but that does not mean that electricity supply is regularly insufficient for my needs. Except for very rare exceptions, everyone can always pull as much power as they currently need. There is no brownout when everyone is cooking in the evening (or whatever). The capacity of the network and generators is also oversold, but utilities still take care to ensure statistically that situations where the actual instantaneous demand is not being met are few and far between. I don't see how the same could not be done with IP connectivity--and how advertising anything for which this cannot be expected to work out is anything but simple deception. If you cannot supply 1 MW of electricity at some point in your network ... how does that legitimize advertising 1 MW connections and then simply lowering the voltage when the customer tries to actually use it? In short: Overselling is fine, as long as your customer doesn't notice, except very rarely under exceptional circumstances. If some product doesn't work under those circumstances, you'll have to raise the price or lower the advertised bandwidth. How else am I, as a customer, supposed to distinguish an offer that effectively is going to deliver only 50 Mb/s from one that actually does 100 Mb/s during peak times, if both are allowed to advertise as "up to 200 Mb/s"? Where is the incentive for ISPs going to come from when there is no limit on how much they can oversubscribe?