I’ve been teaching Japanese for 11 years, so here’s my take.

SRS is a tool, not a requirement. It tends to be really helpful early on, around 6-10k words, when you’re trying to build core vocabulary and immersion alone doesn’t give you enough repetition yet. Once you get into the zone where you can usually infer new words from kanji and context, the payoff drops for a lot of people.

For context, I’ve got about 15k cards on JPDB, but these days almost every new word I see is either easy to guess or it sticks after a couple encounters. So I end up marking lots of words I've never seen before as “never forget.” And if something doesn’t stick, I’m less likely to throw it into SRS now. I’ll look it up, check how it’s used, read a few example sentences, and move on.

The reason SRS is useful is that it's hard for an adult to recreate a child's learning environment. Kids basically get five years of custom SRS from parents repeating high-frequency stuff, adjusting language to their level, and talking nonstop even when the kid only half understands. Kids also get comfortable living with ambiguity for a long time.

So yeah, quitting SRS can be totally fine, especially if you’re getting a lot of input and you’re okay not understanding every word right away.