While I get your point, I think when using Windows, the majority of ibstalled software will be closed source. And most, if not all of them have been granted the same level of priviledge a some point during installation.
The reason this software exists is fundamentally about a lack of trust. We don't trust Microsoft with the level of data that Windows 10 collects. That is a perfectly reasonable position to have. However if that is your opinion, it seems frankly bizarre to trust these nameless developers who have zero accountability for this software. Microsoft is at least accountable to the law, the stock market, and their customers. There is hundreds of billions on the line if they screw you over. If Barnacle screws you over, the only thing on the line is their copy of Ultra Street Fighter IV.
In that order. We are last. In fact I'm not even a customer anymore, I haven't paid for an update to Windows since Windows 8 was released.
When it comes to privacy/security tools, it makes sense to make it open source, since they usually are given an insane amount of privileges to modify your machine.