Re: Errr....
First of all, most of grime going into a PC is not dust it is lint.
1. De-Linting is not filtering, it can and is normally handled by static attraction. Even if you have fine mesh on the intakes (as my desktop PCs and home server do) it holds lint mostly because of static and not mechanical filtering (at least initially, it becomes mechanical as it clogs up).
2. Your typical mesh/holed intake on a PC can stop quite a lot of lint by static alone. It is effectively a form of filter.
3. That quite clearly stops working on a nice fully grounded "cute" metal body which has no paint on top.
Back to Numer 3 - this is what an idiot tax operation victim has bought. They bought a system which has been relieved from household lint protection by design. As the time goes it will get clogged in inside by lint because it ain't sticking to the intake.