Which is all fair enough if what you're after is 'just' a monocular. Solely as a monocular it's not particularly great, just like how solely as camera it's not particularly great.
However, as a monocular-camera hybrid
—something to both see and record sightings within a single device—it's unmatched.
The Powershot Zoom should not be compared to either cameras or monoculars. It should be compared, as maulanawale points out, to things like holding a phone up to a scope, or things like those terrible digital binoculars which have flip-up screens and sensors recycled from outdated phones.
Also, your estimations of magnification are a bit off. The diameter of the optic factors into field of view and apparent
(not literal) magnification, and also 400mm is never
8x magnification. That's a woefully outdated misconception based on the erroneous idea that 50mm is how human eyes see (which has never
been the case and is just a relic of 1930s marketing). In reality, 400mm is
more like 6x real human vision magnification (assuming the human in question has two fully functioning eyeballs with at least 20/20 vision). Also, the effective focal length (and thus magnification) is based on the output file (i.e. 1:1 pixel output) and does not factor in the playback viewing format; looking only through the small screen in the device (which can't display the image 1:1) shows, unsurprisingly, a much smaller image than if you were to view a photo or clip on a computer screen or TV.
So your finding that the Powershot's magnification, when looking through the device's own screen, being close to the 5x10 monocular is to be expected. This is a well documented problem with comparing camera focal lengths to binocular/monocular magnification, as though 400mm is
8x magnification by the photographic 50mm standard, it's not 8x magnification by the standards of binoculars, and never has been, and now that we've also got to factor in the viewing sizes and display densities of digital devices, really the whole comparison gets thrown out the window.