According to IEC 62304, integration testing can be combined with system testing. Therefore, it is possible that integration test results can directly link to system requirements. For clarity it's best to state in the software development plan where integration tests are incorporated in system tests, then don't use term "integration tests" when tests are done on the whole system.
From experience, I think the reason IEC 62304 allows integration tests to be combined with system tests is simple efficiency: for a true non-system integration test, it is necessary to make up dummy input and output devices. Why not just use the real system? If so, the one test covers two purposes: the integration and system. I think this is actually done a lot in practice.
The approach works well for a simple system, where the data flows in a single line from one module to the next e.g. software that measures a sensor, does some signal processing, range checks, and then outputs the result to a display.
The approach does not work well for more complex systems that may have several modules interacting to give a result. In that case, leaving everything to system tests leads to a huge amount of test cases, so that integration testing might be more efficient to reduce the testing load.