We had FaZe, G2, NaVi and mouz as qualifiers. We had VP, BIG, North, Astralis as legends.
I guarantee you if this was done with groups, we'd have ended with at least one overstacked group and at least one group with 4 shit teams, which would not have resulted with such a good play-off bracket as we have now. You'd have 2 bad teams qualifiying, a good team getting knocked out of supergroup, and then 2 good teams meeting early because they came second in the supergroup.
Even if you say "oh scrap the legends thing and seed the groups on world rankings"- North, VP and Astralis are all top 10 teams, and you could still end up with a group like Astralis, VP, Liquid, BIG... and also a group like FaZe, C9, NaVi, SS.
The only thing fairer than Swiss is Round Robin. The only compromise that makes sense time-wise is Swiss with BO3 for every X-2 team in an elimination game. Groups will never, ever be less random than Swiss.