Don't be retarded. They would still need to match it to the range that the user normally logs in from. You would have more luck winning the lotto 50x over than guessing what range of IPs I am normally assigned to by my ISP.
The only way you're going to get my IP is if you have access of my machine or there's a vulnerability in Blizzard's system that allows you to get an IP from someone's battle tag.
You have nothing to back up your claim so you resort to attacking me instead of actual facts. Nice!
Everything I just wrote can be confirmed by Google and reading up on how the internet works.
An ISP will buy a large block of IPs and then allocate them around the regions they serve.
If I have a nation wide ISP and my house is located in Timbuktu California then my ISP's hub that controls internet access for Timbuktu California is going to have a pool of pre-assigned IPs to choose from. Those IPs will never be the same pool from LolLearnToNetwork Texax.
You would need a pretty precise range and it's basically impossible to guess.
Here's some reading material to get started you clown:
You can do the rest of the research yourself.