Cabinet resonance and buzzing of course let one know the speaker is in a box but I'm not sure that's what we're talking about here. More like the 'closed-in' box sound some may or may not exhibit. I think modern boxes are far better and money seems to buy a more open sound regardless.
I've heard Magnepans for over forty years and owned Martin Logan electrostats as mains. If you enjoy 'large' singers and images, great. I sure don't feel they are more accurate.
I went to a good pair of ported boxes and will never, ever go back as they reproduce music far more accurately IMO. And that's after a lifetime of listening and attending shows, so...to each his own opinion.