Yes, because according to the GrapheneOS devs it would weaken the security properties of the OS. Besides, GrapheneOS already supports the native Google Play Se

Yes, because according to the GrapheneOS devs it would weaken the security properties of the OS. Besides, GrapheneOS already supports the native Google Play Services (with additional sandboxing), so I have a hard time seeing how MicroG would help here. (I used MicroG on LineageOS for years and it certainly wasn't without bugs.) Also, regarding what GP wrote, I haven't encountered a single app in a long time that wouldn't run on GrapheneOS.