Since you were never going to join their mailing list, no, you are simply saving them bandwidth. What you don't realise is that x number of people join the lis

Since you were never going to join their mailing list, no, you are simply saving them bandwidth. What you don't realise is that x number of people join the list and x number of people tolerate being spammed with 'did you know we sell stuff' emails every day for the rest of their lives. x number of those people actually do buy something; likley the thing they intended to buy originally but joined the email list in case a discount code would be the subject of the first 'welcome' email because this is what they have been trained to expect. All this has been A/B tested and, thus, has been 'proven' to be great business practice.