For the competent writer, its a useful way to introduce higher and higher stakes. You can even subvert the power scaling by having the protagonist defeat the more powerful foe through intellect or technique (Dragon Ball Z did this a lot).
However, if the writer isn't careful, the power scaling starts to lose meaning as the protagonist and his foes reach unimaginable heights of power.
TLDR: powerscaling is fine as a trope; it depends on how it is used.
