Why would you need to know what someone's rank in 2v2, 3v3 and 4v4 is to seed a 1v1 tournament?
I wouldn't, and I never said I would. When I help seed a 1v1 tournament, I only look at 1v1 ranks.
Where previously I had a massive amount of rank data, now I have far less. Many top players have bagels (0) by one or two of their 1v1 factions, simply because they have been focusing on other factions for the last four weeks. Now I have much less information than I had before, which will make seeding more difficult.