It's really, really not.
I take Makar here quite easily, though I feel it's likely both are being a bit overrated in the big picture. Fox is almost 2 PPG in the last ~10-12 games, him and the team are on a tear. Neither player has put up ONE 82 game season, let alone multiple strung together, worth of being mentioned in the same breath as those guys.
Just because a player hasn't had the opportunity to play a full season doesn't mean they aren't capable of it. I am willing to go on record that Fox will be a hall of famer when all is said and done. This is a special, special player.
Also, if you are going to discount Fox's hot streak, you have to balance that with the fact that he had an 11 game stretch earlier in the season where he registered only 2 assists and the Rangers couldn't buy a goal. If you look at his underlying numbers, nothing is unsustainable. His ES on ice sh% is actually lower this year than it was last year. He far outperformed the expected goals model last year. This year, he's only slightly outperforming xGF, which is typical for highly skilled playmakers like Fox.
So he's actually experiencing worse puck luck than last year and still dominating - he has 48 points in his last 47 games - 7 points ahead of Hedman who is 2nd in defenseman scoring over that time frame:
NHL Stats
The kid is only 40 games into his sophomore season and he's already a career 60 point pace player (79p in 108gp), and that's with going pointless through his first 7 games. His average ice time during his rookie year was only 18:54. This year, it's 24:37. He was getting less than 2 mins of PP time a game last year. This year, he's over 4. So this jump in production might just be from him getting more ice time, especially on the PP.
His career scoring pace puts him 5th among all defenseman since 2000 (min 100 games played).