Yes, but there is a version of Atmos which works fine across ARC, carried by Dolby Digital Plus, which most streaming services use. In fact, the only two cases that require eARC is a blu ray player, or Apple TV, at least right now, and you can change the settings on Apple TV to force the lighter version of Atmos. 

I’m using Google Chromecast as my streaming device...

Sorry, why does that matter? Does it send a Dolby Digital Plus signal to your TV, or a MAT signal to the TV. MAT is the one that requires eARC, Dolby Digital Plus works off of ARC. 

@tripill What specific model TV do you have?

Samsung 65 Inch LED Smart TV U N65H6350 HDTV

Even though your TV is equipped with HDMI ARC, it is too old to support Dolby Atmos. It may even be too old to support 5.1 audio from the Chromecast. So you will need a device like the HDFury Arcana, FeinTech VAX04101 or OREI HDA-935 that will allow the Chromecast to bypass your TV’s limitations and send the audio directly to the Arc. The Arcana is the most widely used of the three options.

Ok thank you!  I might just wait until I upgrade my tv then-- was hoping for a more affordable device...