This is a really standard group/tournament setup.
Dunno how people are getting confused,
It's not the way League (and IEM in specific) usually do it. The way it normally works in League:
Group A has four teams. Each team plays each other team once. They are then ranked by their record in group, with the 1st and 2nd place teams in the group advancing. It's pretty common to have a sudden death situation for the 2nd place slot.
Group B does the same.
After that, everything happens the way it does in this tournament: Group A #1 faces Group B #2, Group B #1 faces Group A #2, standard bracket through to the finish. (The only exception being that double-elimination brackets used to be popular, especially in Europe, meaning that losing teams would drop down to a "lower bracket" and you'd have situations where the Finals were often one team having to take one set while the other team had to take two sets, but... let's not worry about that.)
The only thing that's really that confusing is they keep referring to the "Groups" and "Group Stages" when they were in elimination brackets to begin with: 2 wins to get in, 2 losses and you're out. That's why we had some teams from the "groups" play each other twice, and some of them not play each other at all, which is something that never actually happens in a group/round robin.
Well, that and it's
visually confusing to display the full bracket when you have a "lower bracket" that only feeds into the semi-finals rather than continuing the length of the tournament.