Sadly, I've seen them in other languages that don't have the same problem, because people have picked up the habit without really understanding why and where it should be used.
The rationale is that they make it a compiler error if you accidentally perform an assignment operation ("xyz" = $name) instead of a comparison ("xyz" === $name). The thing is, this is only a significant risk if you adopt the bad habit of performing assignment operations within conditional statements, like this:
if (null !== ($charset = $env->getCharset())) {
if ($var = 1) ...
But since you should be using === in this context, there's really no excuse for using a single...
if ($var === 1) ...
if (null !== ($charset = $env->getCharset())) {
$charset = $env->getCharset();
if ($charset !== null) {
...