Arguably, it can make it less secure by reducing the user's control over what content the browser loads or what scripts it executes. For example, users may be using extensions to selectively replace harmful content (like intrusive JavaScript, tracking) with benign content. It is a balance between security for the user and security for the website owner.

In the current browser landscape I would think not. Firefox is no less secure than Chrome or Safari and both are subject to economic incentives. You could even argue these issues negatively relate to security as well.