Presumably he's referring to the rising 'Rating' for Multi-Player (Currently 1809 as the highest). It does seem to be a steady (if slow) rise.
That's not a problem at all. Your rating is constrained by your ability to beat people at around your rating, right? Say I'm rated 1900 and everyone else is rated 1700 or lower, my rating won't be able to increase much because none of my wins mean anything. But now if 10,000 more players join the community, some of them might be 1800+ skill level, and then by beating them, my rating can increase. Is this inflation? Not really—a rating of 1,000 means exactly what it meant before (at least, relative the board meta). The currently increasing ratings at the highest tiers are an indicator that more and more players are making it to 1400+ and feeding the ratings of the strongest players. Basically, the highest ratings are a function of both the skill of the strongest players and the size of their pool of competition. You see this in chess as well. Magnus Carlsen's actual skill level might rate him around 2950, but it'll be incredibly hard for him to get there if he can only play people rated in the 2700s.
Whenever someone gains rating, someone else loses rating, so if all players remain in the system then there should be no overall inflation. The problem of course is that not all players remain in the system. Generally, the players with high ratings keep playing, whereas the ones with low ratings might give up on the game and stop playing after giving up a bunch of ratings points to the higher rated players. That would lead to inflation. The other thing is that even if they don't stop playing entirely, the lower rated players probably play less than the higher rated players, particularly multiplayer. So if you look around the multiplayer lobby, you are likely to see lots more representation from high-rated players than low-rated. The other factor is simply that the top player's decks are still getting better and more consistent, so their rise in rating is deserved in most cases. Whereas a few weeks ago they might have had 10-t0-1 odds of beating a newbie, now they might have more like 20-to-1 odds, which is reflected in a higher rating.
