When it comes to web design the most important consideration is the user. It doesn’t matter how cool you or the designer thinks something is if the user doesn’t like it.
Huge companies sometimes spend millions developing products that people ultimately hate.
One such thing is sliders. Something you see on the majority of sites these days. If you don’t know what it is, it’s scrolling slideshow at the top of a site. They’re so prevalent that some clients will fight to include one. No matter what you tell them, they must have one.
Sliders started when marketers wanted to fit as many offers above the fold as they could. This is the most valuable part of a website. It’s what the user sees first and if they don’t scroll any further it’s all they’ll see.
In short, because they feel like ads and web users have been conditioned to ignore ads they cause banner blindness. In most cases they don’t even look at them.
Instead of focusing attention you’re splitting it between all these offers.
Think about when you last had an animated section of a site and were trying to read something. Every time that thing moves, you lose focus.
They take control away from the user (which they hate). They take up valuable real estate that very rarely gets clicked on. If that’s not enough. They hurt SEO, don’t always work well on mobile.