it's more important than you think. Seeding matters a lot. I agree that it doesn't matter as much, but it's not minimal by any means. Also, people still can judge TenZ's individual ability. Your argument really only applies to teams as a whole not going all out/showing new strats. These people are talking about TenZ, and his personal performance. It's not like TenZ was throwing because the match "didn't matter" (which, again, still does).
While I agree with you mostly, using 'seeding match' as an excuse isn't valid.