If it actually £5 a month, but first six months are free. Big distinction.
And that includes the £5 discount for being a EE customer and the geographic pricing variation they have.
Plusnet is doing a £5 a month promotion on its unlimited, so another provider thinks it possible.
The loss leader comments people are making are 100% correct, the pricing for WBC is public record.
Honestly though, you need to continue discussion in the numerous other threads you have. Because it is increasingly looking like you are spamming in an effort to promote the EE offer. You may not be, but it could be seen that way.