Full Idea
If all the forces are to combine, at some point they must all be the same strength, and Supersymmetry (SuSy) makes this happen.
Gist of Idea
To combine the forces, they must all be the same strength at some point
Source
Gavin Hesketh (The Particle Zoo [2016], 10)
Book Reference
Hesketh,Gavin: 'The Particle Zoo' [Quercus 2016], p.242
A Reaction
This sounds like an impressive reason for favouring supersymmetry - as long as you have an a priori preference for everything combining.