I wasn't aware of this feature in UBO, but it doesn't seem to be quite the same. As best I can tell (with a quick test), UBO lets me turn all scripts on or off for a site. I don't see any sort of granular controls for selecting which domains to load scripts from (and I might just be missing it). For example, I may want to allow first party scripts to run on a site and maybe third party scripts from one or two domains. But, I don't want scripts from other third party domains to execute. It's very much a fine grained, least privileged style of script management. It's a lot more work, as you often have to spend a few minutes sussing out which domains need to be whitelisted to allow a site to reach minimum functionality; but, you are not often caught offguard by a site doing strange things on your system.