Meh.. So I'm a Fire Main. I disagree with you quite strongly but not because of what you said- I believe your view on certain things is actually not at all accurate to how the game is played.

So look at it from this perspective, lets refer to the Fire Mains Sealing Jutsu, it got a buff that actually made it a useful mystery as using before, it was a flat out useless mystery, this isn't a bias & I'll explain why, because everyone generally uses immunity & in that meta the mystery was useless- so they buff it to bypass immunities- that's a decent buff but it's not game breaking one- nor needed, because of the way Fire Main is played in the current meta.
Lets explain this further, every Fire Main will always run Mirror Vision, every Lightning Main will run Root of the Warrior, every Wind Main- Flower Guard, there's no alternative to this, that's what creates a "meta", something easily & widely used that is common because it "Works" very well & the only exception to this are certain teams that cleanse, Shields & Buffs battlefield wide(Which would be considered a counter to the meta) or if you're hard balling a R1 blitz team & the reason for this is because you can't plan ahead, so you form your team around a "One Team Fits all" scenario.

Now this is where I think the developers are kinda miff when it comes to actually trying to make things useful while not understanding why the current meta exists, Mirror provides immunity, it's an Immunity meta- meta on Naruto revolves around "Best possible outcome", because you can't plan ahead in Naruto you have to then take a route that'll win you the round in most situations & Mirror Vision fits that role, Root of the Warrior, Flower Guard etc. they will always be more or less mandatory & that's because of another problem that is compounded onto it all, hard CC- which is mandatory to win a fight, especially if you out initiate & also the build up to Round 2..

This is where the key problem area lies, to win, you will always select the "best" possible mystery & in every instance that will be Mirror Vision, unless you can somehow provide a ninja that does what Mirror Vision does as a replacement.

This brings me to my next point, the more people that start building teams around clearing buffs with Kage Summit Tobi- if it gets to a point where everyone is using this Ninja or another Ninja appears that's easier to get that works just as well, that is the only way for a meta to shift enough to counter the current "Immunity meta", obviously it goes deeper than this but the immunity meta is around because Hard CC(Crowd Control) in Naruto, is huge- Immunity is actually a solution for the huge amount of CC in the game, every chase has some form of Immobile or Acupuncture, every ninja has some form of Poison or Ignition & due to the nature of some of these de-buffs not clearing on the next round the only real solution to counter CC is Immunity- hence "meta".

It's why also everything is played so much besides Water main, because it's the only class that doesn't provide some sort of "Defensive" mechanism but provides a lot of de-buffs. This is also why, even though Water Main got buffed- it wont be used, because it's bull* is still countered by Immunity & CC.That said, if you c*e Shark Bomb with Kage Summit Tobi & have higher Initiative, you potentially have chaos every round, nature of the game.
Also a note, the developers of course most likely have some people testing- but this is a game that we get ported, things are a lot different in China & also "Pro Players"?
That's not a thing on this game, there's a reason why I'll always refer to "Space-Time" as "The Battle of the Whales", it's not a skill based game, it's a who can pay the most- this inherently fosters anti-competitive things by default, this game will never have any kind of "Professional scene".

c*e c*e c*e