Skyrock, two main reasons for 17, in no particular order of priority.
1) I live on the southern border of the
Great North Woods that extends
from here into Quebec then north toward Newfoundland and Labrador.
Translation: that means really, really thick woods, mostly conifer (especially fir, and going north, spruce, so low and close to the ground), especially second growth like you find after a cut. That means it's really, really hard to walk in those woods while carrying anything longer than your arm. Add major hills left by glaciers (moraines), boulders, ledges, swamps, marshes, mud (now is mud season here), blackflies and mosquitos ...
If you've never walked in the GNW, but want to get a sense of density, take I-95 north out of Boston into Maine, two hours past Portland to where it bends eastward -- toward Bangor, the gateway to 'downeast Maine' and the northwestern highlands.
Several points along the drive from Newport to Bangor, you will see the GNW, and might "get it" about 17.
2) I like short barreled rifles.