I don't have any of these devices, but it seems to me that "smart" is used to mean different things for them. For the Amazon Echo and Google Home, "smart" refers to the assistant itself and not the speaker which is really only there so you can hear the assistant. As speakers, these two are awful.
With the HomePod, "smart" refers to the speaker sound and how it tailors automatically to where it is in the room (and if there is a second one). As an assistant, the HomePod is weak.
And where is Sonos on this chart? The Songs One has an assistant built in (Alexa). And the speaker is good, if not really "smart" like the HomePod. Seems like if you're going to go to the trouble to make the HomePod fit on this chart, you should also fit Sonos. Unless CIRP is just looking for that juicy Apple click-bait.