I don’t think it’s universally true. Yes, people do often run a whatever-core 2-10k Anki deck, but at least online I noticed so much emphasis on immersion that I don’t think kanji specifically is the focus. It’s getting to understand as much Japanese as possible, as quickly as possible to be able to enjoy content in it more.
That would suggest the priority is listening comprehension.
You don’t need WaniKani to watch anime without subtitles. You need to grind vocab to be able to understand what’s happening in the series and/or watch the series with Japanese subtitles to grasp how the phonetics relate to the kanji. Before any of that you would need to know hiragana and katakana very well.
Grammar and WaniKani are different things. If the overarching goal is watching anime without subs, grammar is way more important than WaniKani.
Here the problem is the overall approach. It’s the gamification, not the actual learning process that draws you to WaniKani. There are apps like that for grammar, but it’s way better to learn some grammar and then learn its usage from native context - watching/listening/reading. Apps are based on whatever 1:1 gloss/card matching which is by definition imperfect and the variety of input you get from them is limited.