>>33813975That's because of how oppressive this year's VGC evironment is. If you have no clean counter to the likes of Kartana, Bulu and Celesteela your team is absolute garbage and you will lose period.
Notice how the top 10 is basically a playground for UBs and Tapus. The whole meta revolves around them, pokemon such as Garchomp and Arcanine are just consequences.
To add, even if a weaker pokemon (Arcanine itself for example) gets high usage, its presence won't be so overwhelming to the balance due to them lacking the stats and/or movepool.
Since we're talking about VGC, a good comparison is 13 and 15, the lack of megas (Kangaskhan, Gardevoir and Charizard, specifically) allowed the meta to be much more diverse because it was less oppressive to play (less "counter this, that and that or auto-lose").
tl;dr a few overwhelming pokemon makes the meta less flexible
