Why most of the people recommend genesis framework based themes?

These day's I'm considering to purchase a good WP theme. Most of the online bloggers recommend genesis framework. However it's more expensive than other premium themes. I guess most of the bloggers recommending it cause its affiliates.

According to my reading this framework optimized for better SEO. But I think we can use good SEO plug-in to optimize the WordPress. Are there any specialty than these things in genesis themes framework? Something like fast page loading, lower resource usage, clean codes with w3c validation etc?

Thanks!