Why does .new initialize?

[Peter Scott]

I'm curious as to why Rat.new initializes instead of leaving as undefined:
> $*RAKU
Raku (6.d)
> my Rat $p
(Rat)
> put $p
Use of uninitialized value $p of type Rat in string context.
Methods .^name, .raku, .gist, or .say can be used to stringify it to 
something meaningful.
  in block <unit> at <unknown file> line 1
> my $q = Rat.new
0
> put $q
0

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Peter Scott