If by notifications you are referring to Firebase Cloud Messaging, which replaced Google Cloud Messaging and is now integrated in Google Play Services, I do agree with you.
It is my opinion that Google should be forced to decouple all these Google Play Services which are not related to the "Online App-Store" which Google Play is, and ideally be forced to open source it, so that trustworthy alternatives can be used to replace it.
I mean all the components which track you, which basically is what Google Play Services is: it is a system service created to monitor every possible activity you have with your phone (location, physical activity, health) as well as the efficient, persistent data connection to transfer these bits of information to Google (and to your device as FCM), while Google grants you access to use these services in a restricted manner.
For me Amazon's Android devices are basically useless since they don't have Google Play Services installed, and you have to work around it to get it installed, which basically is illegal to do.