Yes you can.
WordPress can be your base or pilot to begin .
But soon to scale the website you will be making lot of changes in the codes .
WordPress will not be able to support you .
You may need to scale up the wordpress , or create new custom framework for scalability .
but it’s good place to start.
Also Yahoo , is not mere website , it has search engines, mail servers. new brodcasting/feeds , CMS, lot of high traffic puling solutions.