With all of the problems the game has got (lack of GW (as much as I hated it)), you introduced IMMORTALS! Frankly, they’re worse than the likes of Stella/Zuul/Cathy/Tak etc combined.
Not even I want whatever you folk were smoking when you thought those ones up.
Hint: Fix existing issues before introducing new crap we have to deal with.
/aside
Not my original title, you your forum software complained my title was too short.
They were literally thinking “what can we make a into a quick cash grab this time?”
Its part of the never ending cycle of “lets introduce a new limited resource/currency for a quick buck”.
The immortal troops are a way to push burning marks and the pvp premium season pass, in hopes that people will pay money to get additional burning marks in the slight hope of getting immortal souls to level up these troops.
Probably in the next major update or the one after, we will get another new currency/resource as the revenue they get dies down so they have to create another new cash grab.
Once upon a time, troop strength balance maintenance was a key dev objective. No longer. Pandora’s proverbial box has been opened, and we now have escalating weapons and troops of mass destruction.
And they all can be yours today for a reasonable 
price
Any game that’s been around as long as Gems of War has that continually introduces new mechanics and new content eventually suffers from this. It’s an impossible task to balance things so perfectly that you don’t fall into either a “vicious cycle” of new content that’s underpowered as compared to what came before or a “virtuous cycle” in which the new content keeps exceeding what the older content can do. And most games like this one will err on the side of the latter, because the opposite direction makes it more difficult to attract and retain new players when the “legacy players” will always have the best stuff on account of having been there so long.
And that balancing job? As somebody who did it for a while a few decades ago for one of the early (text-only) Multi User Dungeons that were popular in the early days of the internet, it’s probably the most thankless job one can imagine, at least as compared to anything else involved in the game short of being the “bad cop” whose only job is to wield the ban-hammer and punish people for every infraction, large and small, real and imagined. Because no matter how that adjudicator/balancer does his job, people are going to be unhappy about the results and complain about it, and those people who complain are far more numerous and vocal than the people who will stop and say “thank you” or “job well done”.
Wow and they do all that for free? Amazing!
Unless they get some sort of compensation (maybe monetarily?) for doing it. Then I think you’re describing a “job” 
I agree that Sirrian doesn’t deserve to do a live “roast” which is what a Q&A in this current climate would prolly be.
Note: this isn’t meant to be snarky towards anyone. All in good fun 