Because if it uses the same browser binary as your other web apps (tabs or other DeskGap apps), the OS can share memory between them. Not possible with electron since every app bundles its own Chromium binary.
Of course they can. This is what OS engineers have spent decades thinking about and optimizing. And then stuff like Electron appears and circumvents all those optimizations. Which is the main reason I dislike it.
Sure, but with sandboxing and technologies such as Firefox Containers, containers in general (such as Docker), and VMs (together with a secure enclave such as utilized in Qubes) it can all be thrown in the trash bin. Its just a matter of time until that's the norm. iOS is already on top of doing sandboxing well.
Shared memory is "a method of conserving memory space by directing accesses to what would ordinarily be copies of a piece of data to a single instance instead, by using virtual memory mappings or with explicit support of the program in question. This is most often used for shared libraries and for Execute in place (XIP)" according to Wikipedia.
