THIS IS HOW SEEDING WORKS. In every sport, not only in eSports. If you are at the top of the last major, you get the best seed. OR, in case of this major, the teams decided each other's seed by placing them in ranks from 1 to 15.
Oh and by the way, NRG are sitting at 0-2 right now, in no circumstance have they been performing good in this major. So if you want an excuse that NIP are not in the same place as Astralis right now, it is - they are a worse team. Fucking deal with it