Just as an illustration, see the printout of lightbeam (addon that shows the sites you visit, and the resources (cdn, fonts, etc) they take from the cloud. These are 200 pages/subpages I visit almost daily, for work and leisure (all mainstream). For my research I have similar pics in sp52. If you visit those sites without proper settings, the app will show not the neat balls you see below, but a bunch of interconnected meshes made of sites, and of the common resources they use to keep our attention. To avoid that interconnection means privacy. But that information remain in your isp, and the multiple cloud-spaces where (generic) you have most of your data, which makes that information a security issue. For that reason, site/tab isolation (containerization) is a must. And for that reason, you should use, if your hardware allows, multiprocess.