The "blues" is a state of mind, body, and soul, not a make/model of guitar.
The bluesmen of old played out their feelings on all kinds of guitars, and usually the only common factor was "cheap," a condition of their disposable income.
In the '20s (of the last century), cheap meant small bodied and mahogany, characteristics that also produced cutting treble and mid notes that were sharp and clear and didn't linger or pile up on each other or bump into the vocals. Back then, these included the Martin 2-17 and the Gibson L-0. In the '40's, Martin introduced its 15 series of "austerity" guitars.
I guess there are three reasons to seek out a "blues" guitar: 1.) to reproduce or mimic an original sound of the blues, or 2.) to "look" the part while performing (along with the requisite fedora of course), or 3.) both. And there's nothing wrong with any of those reasons.
But the bottomline is that the blues can sound good played on any guitar, including big rosewood dreads. It's all about the execution.