N_Cook wrote:

I would suggest that it is due
to forcing the air to follow a tortuous path so a generic design flaw.

That's what causes the high back pressure (and hence low air flow). For good
cooling the airflow path should be in a striaght line with air vents in and out
as large as possible (consistent with safety regs) and there are some other cute
aspects which are even less well known too.

Graham