That may very well be the case, but isn't this a solvable problem? Just like apps made in C need to be protected against buffer overflows, apps made in JS need to be protected against XSS. Both are reasonable threats that can be mitigated.
Yes, but just because it can be mitigated doesn't mean that it is mitigated.
Sure, but I just want to point to the fact that this is a solvable problem. A lot of people talk as if it is some sort of insurmountable obstacle, whereas I think responsible programmers can solve it and move on.
A defence is always only as strong as the weakest link, and an attacker usually has all the time in the world to find and exploit it.
Optimism has no place here.