Stereobasic Youtube and YT Music are different in this regard as these are Google apps - if I am not completely mistaken, Google actually demands manufacturers to have a specific suit of their apps pre-installed in order being allowed to use the Google services, including the whole Play Store. So Nothing can’t really remove those apps as they wish, since they’d lose access to Google Play.
Netflix is a different matter hower. I actually never heard about they want to restrict best quality on phones only which have their app pre-installed. For me it would be just another reason to avoid their ever price increasing service completely. If they are being successful, others will follow.