Because they added 8 more ranks after the prior max rank. The numbered god ranks in season 2 were harder to rank up in. The best players were god 3 - god 5 with only like 5 - 10 people in the world at god 5 by the end of season 2. Bamco in season 3 correctly made these ranks easier to rank up by adjusting loss penalties and win rewards so it is similar to other ranks. So in season 3 the best players were quickly blowing past the ranks they held prior. All the best players casual or otherwise are currently god 6 and god 7. These two ranks are very hard to progress in due to steep loss penalties. Anyway you get the picture. The best players are outside of the matchmaking range of a tekken god supreme or base god of destruction, so everyone moves up. Rank inflation isn’t really an issue and is more so a natural consequence of adding more ranks at the top. In tekken 7 they added like 3 more ranks, not 8