"On the other hand my Facebook username is just my email address. Never going to forget that." For the audience Yahoo serves it isn't as plain and simple as th

"On the other hand my Facebook username is just my email address. Never going to forget that." For the audience Yahoo serves it isn't as plain and simple as that. They probably don't own their own domains and run a mail account through that domain - so it's more likely that they'll have an email addresss 'given' to them by their ISP when they signed up for internet access. So although their email address will be easily remembered during the point they signed up, things get very confusing when these visitors move to a different ISP for a variety of different reasons, and thus lose their previous email address with their previous ISP, and gain a new email address with their new ISP. You, here, are more of an exception to the rule of the typical Yahoo audience.