For me, the primary concerns are security and trust. Every sandbox has holes. And the provenance of Javascript on the web is often somewhere between lackadais

For me, the primary concerns are security and trust. Every sandbox has holes. And the provenance of Javascript on the web is often somewhere between lackadaisical to highly suspect. I wouldn't mind ad-supported content, if the ads were secure, not annoying, and didn't per force track me in ways I don't want. And there's part of the trust aspect. I expect to know what my browser is doing and what data it's sharing. Current scripting takes that way past my comfort level. I enable scripting selectively. And if some page/site seems to use it for no other reason than to dump unvetted third-party content on me and to track me, forgetaboutit.