Don't think most users know or care about security or HTML features so while certainly it's a difference it's unlikely to be important for most users. Think of

Don't think most users know or care about security or HTML features so while certainly it's a difference it's unlikely to be important for most users. Think of Safari as a skin that's unbundled from the engine. While Chrome or Firefox are reliant on Apple to update the engine, so is Safari, but neither are reliant on Apple for other functionality that they want to implement that users can take advantage of. IMO it's modular enough.