People just need to properly set expectations. I've been using Duolingo for about 15 mins per day on average for a few years now. What I've found is that my reading skills are actually pretty good (roughly A2/B1 level), for instance I can open up a Spanish language subreddit and mostly make out what's going on. My listening is rudimentary at best, I can generally have a vague idea of what people are talking about if I listen to a Spanish conversation. My speaking is almost nonexistent.

But you know what? That makes sense. I'm mostly just reading text and clicking words to fill in the blanks. And the listening component is so unrealistic that it barely builds anything up. And I don't do speaking at all.

As you say, it beats doomscrolling. For a free service I'm not expecting that I can parachute into a Spanish speaking country and be fluent. At the same time, I'm a lot better in terms of my skill level than I would have been otherwise.

I have friends and family who earnestly desire to learn a language, and ask me what to use. They often end up choosing Duolingo and make no progress toward fluency in the subsequent years. The criticism is that it subverts their goal, preventing their success by replacing learning with addictive behaviors that don't educate (like someone wanting to enter a new field and getting hooked on "educational" YouTube Shorts podcast clips). It also spoils their ability to focus on alternative learning methods as none deliver as much of an immediate dopamine rush as Duolingo. These alternatives could do better at that, sure, but it doesn't change that Duolingo fries their brains preventing them from adopting productive methods without therapeutic interventions.

That's why people advocate against it and advocate for alternatives.

Their goal wasn't to defeat doomscrolling, it was to learn a language!

That's a very, very low bar though.

Exactly. I know I’m not learning much. But it is a healthy/less harmful distraction and I managed to read some Spanish tweet. Can’t complain.

Sitting in an empty room beats doomscrolling!

I agree. But should they wish to go beyond "beating doomscrolling", they have other options

A language learning platform that works would be nice, instead of this.

It's not much better for language learning than just playing Candy Crush. As long as you don't delude yourself into thinking this is time spent productively, then sure.