What is a canonical representation?
Canonical form basically holds every variable in its group.
So if you have three variables named A, B and C, your SoM could be A~BC+~ABC+AB~C = Y.
Now you can simplify this to reduce the number of variables in the equation. This simplification is easy for us to solve manually. But for a computer, it needs to know the A, B and C values as a group (101+011+110 from the example above). Because of this, canonical form holds significance.
If you simplify, it just becomes a normal Boolean expression and not a canonical form