Not really true. There are more leaks than calling malloc() and failing to call free().

Any function call that returns a handle (to a possibly statically allocated resource) will consume a resource, that may be leaked.

Anything that has a file system and uses temporary files can create leaks that may even accumulate despite a cold start of the device.

But a tool for statically analys of code can look for a lot more errors. This may include:
- Code that disables interrupts and potentially don't enable interrupts again.
- Code that locks a resource and potentially doesn't unlock the resource.