Its sad to compare to hearthstone since its still casual, but since its the biggest name in digital cards its relevant.
I've followed some of their tourneys, since each player gets to bring with them 4 decks to use, with one banned by the other opponent, by very definition, there are a minimum of 4 viable decks at the highest tier of HS competition. Since there is a minimum of 1 competitive deck possible for each hero, that means at minimum 9 viable decks. Since there are many classes where 2 deck archetypes are viable and seen in competitive, this makes the number larger. IW has had at most 5 viable decks at one time, with many factions completely useless basically.
I'd also consider chat separate from emotes, one is built into the game, the other isn't. Also with chat, it runs the risk of needing to be a complete asshole to be effective as part of gameplay.
It's not that each player gets
to bring 4 decks, it's more like every player must
bring 4 decks. And if you want to see how skewed their top tier meta is, pay attention to what class is consistently banned during a tournament. This time everyone was banning Hunters, last big tourney everyone was banning Rouges, etc,
If we conducted an IW tourney in the same manner, everyone would be forced to bring 4 decks where no two decks could share the same 3 purities, and then each player would get to ban a whole faction. This would force people to play a wider variety of decks for sure, but forcing variety into top tier play is not the same as having a larger selection of viable decks. Instead of banning Hunters, players in IW would just be banning Overseers.