I think people have different definitions of soundstage. IMO, it means a speaker's ability to portray the musicians in the places they were put in the recording so instruments can be identified by location.
That sounds more like what I'd call "imaging", namely, the precision and accuracy of the musicians' apparent placement relative to each other ... and within the soundstage. I think of "soundstage" as the 3D space bounding this placement. Presumably, most audiophiles want a soundstage with the greatest apparent breadth, depth, and height achievable for playback of any given recording. But presumably they also want sharply defined images, along with the illusion that the speakers disappear within the soundstage.
The Bose direct-reflecting design can achieve a big apparent soundstage even from very small satellite speakers along with a single subwoofer. That may sound impressive and pleasant at first listen, but I wouldn't expect very precise, accurate imaging (or frequency response) from that approach. Admittedly I have not listened to Bose speakers for many years or in a wide variety of settings.
On the other hand, I had a pair of Totem Arros, which are small floor standers with a reputation for excellent imaging. I found they did indeed consistently produce a sharp center image and the speakers did indeed seem to disappear within the soundstage. However, the soundstage was not especially wide, deep, or high (at least not in my set-up). Furthermore, the skinny boxes could only accommodate 4.5" woofers, which limited the bass impact.
Lots of factors and trade-offs.
