Why? I find it absolutely horrendous personally and would avoid any webpage that used it (got to the end of the presentation on my second try as I literally rage quit the first time).

Some reasons as to why I severely dislike it: 1) When it scrolls the background changes color. There's multiple transitions going on. It's sort of like going to a different website. I lose my entire concentration and interest. 2) No scroll bar. I can't get to the final slide without painfully going slide by slide. 3) When scrolling with the mouse, I lose control of the webpage for about a second. I can keep spinning the mouse wheel but nothing is happening. It's infuriating.