Disabling the useragent may break some stuff that many sites still do server-side.
Disabling referer may break downloads and images on many sites. You'd think they'd all be able to support blank or non-existent referrers, but many large CDNs only support whitelisting specific REFERER strings (not blank ones). We'll be turning referrer blocking back on for one of my big sites shortly because we have other sites linking directly to file downloads (of 60MB and up) and hotlinking images.
Disabling referer may break downloads and images on many sites. You'd think they'd all be able to support blank or non-existent referrers, but many large CDNs only support whitelisting specific REFERER strings (not blank ones). We'll be turning referrer blocking back on for one of my big sites shortly because we have other sites linking directly to file downloads (of 60MB and up) and hotlinking images.