Why can I still not control Google music and Chromecast audio from my voice?

I have a Google watch, a Google phone, a Google music subscription, a Google TV and Google speakers. Pretty much the only thing I want to do with Google assistant or OK Google is play music on my speakers while I'm cooking and my hands are too busy/messy to touch my phone, but Google can't make these devices/services work together with voice control.

Google: Instead of focusing on getting your AI to tell jokes, how about you make it do something, anything, for those of us who have been buying your crap for years!