WordPress has many disadvantages, why do people like to use it?

Yes I use wordpress too why? Theres no other free good alternative to it in the moment I hope better free cms coming out.

Found some interesting on the web: zuliewrites.com, check it you will be impressed of that fast page load speed, it's a squarespace site.
Maybe squarespace had done some improvings on their platform?

This is like complaining why your ferrari can't handle your farming jobs? Because it wasn't meant to!

300,000 pages of what, articles .. static pages is the way to go

Videos, servers and database optimization.

Wordpress is just a cms built on php language. Nothing less, nothing more.