it is a tournament system for spectators, not players. let's take a look at a few different tournament formats first -

single-elimination (single-KO): the only meaningful result is the first place. the second "strongest" team will often not reach the finals, they might face the future winner in round 1 and get kicked out at the start. same as #3 and #4 and suddenly you have boring-to-watch finals with a team that got a lot of draw luck.

round robin (everyone against everyone): this is the best format to provide a meaningful result for every place. it has no "final series", so you cannot build up hype for spectators, and if you don't know the good teams in advance then you will miss a lot of "high quality" matches. also towards the end many matches will be straight up meaningless since a win or loss might only change your placement from #13 to #12 out of 16 while team #1 is 2 wins ahead of everyone and has only 1 more game to play (they can just gg out at the game start and still win). this format is sometimes used for group stages in dota - don't bet on those games at the end due to the mentioned reasons.

double-elimination: gives much higher chances to keep the 2 best teams until the very end in the tournament. #grandfinalshype. you have "this one match" with the best teams that everyone is going to watch. the biggest issue with this format is the same as single-elimination - results for place 3 and lower are sort of meaningless.

now, if half of the best teams get knocked out in round 1 or 2 then people won't watch the majority of the tournament. seeding (based on group stage results or rating) try to avoid this situation by pairing strong teams with weaker ones at the start.

now take a look at the seeding for the major - the teams that start in the lower bracket are the ones with the worst results in the group stage, they are to be expected the weakest teams. half of these "worst" teams will drop out after 1 round. in round 2 the remaining "bad" teams get to play against a potential #3rd place who just lost a game against the potential #1. this is a format for spectators - after 2 rounds the presumably 8 weaker teams will be knocked out and the remaining games are "high quality" with the "better" teams.