Yes. Also, they don't need much vocabulary, no grammar concerns, no reading/writing.
We much overestimate how well kids learn, and how "easy" is for them.
Many kids have language difficulties, and they usually know, and they don't feel too great about it.
I am working in this space as well.
Habit formation / self-learning is a big easy because overwhelming majority of people prefers more structured / guided content. This makes SRS very niche.
The part of seeing "You still need to decide what’s worth remembering" as friction I strongly disagree with.
That is a very important part of the learning process and IMO should not be automated. It is difficult because learning is difficult, but if you kill that you also kill the spirit of self-learning!
And not mentioned in the article, but I think the most important factor is that everyone in the SRS niche knows Anki, and despite Anki faults, everyone has put the effort to learn how to use it, got used to it, found a good-enough workflow, and have zero incentive to move to a more expensive alternative even if it is better.
Same problem as dating apps: if you could actually learn a language with Duolingo, then you would stop using Duolingo. No good for business.
The hard part is how to trick people into believing that it works or even "it's better than nothing". Hence gamification.