There are exceptions. The Boys, for instance, succeeded due to it not being a faithful adaptation.

Don't get me wrong, the books are fine for what they are, but the only people who'd enjoy (or even tolerate for more than a couple episodes without getting physically sick) a faithfully adapted Garth Ennis book are probably the same that think Homelander is the good guy, who thankfully seem to be a minority.

Or another one: I very much doubt a faithfully adapted Do Androids Dream of Electric Sheep film could have achieved the cult classic status of Blade Runner; as much of a staple of science fiction as Philip K. Dick is, he's a bit of an acquired taste, and most viewers would probably fall asleep halfway through a faithful adaptation, long after having lost any trace of the plot...