This sort of stuff does tend to work at least slightly and to start with. Windows is a dire shitstorm of mess inside from WinSxS to the whole registry mess which everything hooks into and it crawls to a halt. Everything from shell extensions to screwed up COM registrations slowly shaft the entire platform. Most professionals know not to fight the battle and just reinstall the damn thing. I spent enough years fighting it.
Unfortunately the usual story is that the company sells a legit cleaner product onto the market, finds they can't compete with the 2 million other products out there doing exactly the same thing, find they have several pissed off VCs on their ass and proceed to ship malware and toolbars with it to break even. Then it joins the slurry of PC fix utilities that people install ten different copies of after googling it and then bring it to me because it's even worse.
Genuinely these things start with good intentions but ignorance of the whole state of affairs.