What is the use of intent-filter in the manifest for a service?

I am in a train and suddenly thought of something.

If I am allowed to declare my service as below:

<service
    android:name=".service.MyService"
    android:enabled="true"
    android:exported="true">
    <intent-filter>
        <action android:name="INTENT_SAMPLE" />
        <category android:name="android.intent.category.DEFAULT" />
        <data android:mimeType="text/plain" />
    </intent-filter>
</service>

I know that doing below will result to IllegalArgumentException: Service Intent must be explicit error.

Intent intent = new Intent("INTENT_SAMPLE");
intent.setType("text/plain");
startService(intent);

Then, what is the use of intent-filter in this case, if there is any?

from What is the use of intent-filter in the manifest for a service?