There is no good reason to create a new object to not do anything with it. Most of the time, this is due to a missing piece of code and so could lead to an unexpected behavior in production.

Noncompliant Code Example

if ($x < 0) {
  new foo;  // Noncompliant
}

Compliant Solution

$var = NULL;
if ($x < 0) {
  $var = new foo;
}