That's not inherent to PHP, but rather the ecosystem it's usually used in. The standard "LAMP" stack, for example, has Apache in it for the actual server, talking to PHP using a CGI interface. So if your PHP script crashes or hangs, the server itself is still up, and capable of serving other clients.

If you set up a Node script where e.g. Express talks directly to the clients, then yes, the script crashing or hanging means the server becomes unavailable or unresponsive. However, you can also set up a layer in front of Node. See cgi-node for replicating the CGI workflow you might be used to.

There are some advantages to the standard Node model though: the program can manage its own resources, such as keeping a database connection open; it can run asynchronous maintenance tasks; it can see and report the current server load; it can easily combine HTTP(S) communication and Web socket streams; etc.