Akariss is really good at the game, and he knows a lot - don’t discount what he says just because his advice is often different than what you find at gamepress or what is considered “conventional wisdom”. He’s a very deep thinker, and he plays AR very well. Like, he almost never loses a match, or even a single unit.
Having said that, when it comes to his builds, he is often trying to do a few things
a) Show builds most people could do with little monetary investment to achieve a similar goal
b) Give you more reasons NOT to spend/waste your orbs
And I think his advice accomplishes those goals quite well, as people are usually WAY too sucked into the hype-train and spend orbs recklessly, especially 9 or so days before a mythic banner where they are likely to get 3x the number of 5-stars for the same orbs.
Like really, how many times have you spent a ton of orbs into a unit you thought you absolutely “had to have” only to have it benched a week or so later, never to be seen again in any game mode? It happens all the time. Sadly, in order for there to be good units, there must be bad ones - and there are a lot of them. Even the beast units and the crazy hype around those see almost no play. I haven’t seen a Tibarn anywhere other than in my barracks for an entire month. And people who use Reyson do so because he was demoted, and it’s not even for beast teams. Panne only saw some play because she was a bonus unit. This happens all the time.
At least with a mythic banner, a lot of the units being run are proven units where you already know their value, thus your capacity to make good decisions with your orbs is increased dramatically, and the amount of value you will receive in both the short and long-term will be many magnitudes better following his advice.