Websites are at least supposedly are sandboxed so they are not as much of a risk as running native binaries. But this is getting worse and worse though as browsers expose more and more of their host operating system's functionality. The benefits of using a website instead of a native app are quickly disappearing, while the drawbacks have only been somewhat mitigated. We're getting to the point where browsers are worthy of the decades old criticism Emacs has received. They have eventually become an OS with many fine features - simply lacking a good web browser. For the privacy (and security) conscious user, modern web technologies will undermine you every step of the way, or simply break if you choose to stand your ground.