I used it for language learning and CS among other things. The thing is, life gets busy. Suddenly you have a kid or two. Spaced Repetition falls into the same category of things that people in their 20s do because they have too much time, like using intricate note taking systems, journaling, training for triathlons and being really into artisanal coffee.
I haven't found that at all. I'm well past my twenties but find Anki is one of the things I can fit in, mainly because even with kids and responsibilities you can often find small periods (say 15 mins) of time through the day. It's not enough time to sit down and start into something really complex, especially as the time is sometimes interrupted, but it is enough time to try a few questions.
I guess it just boils down to what you want to do with your spare time. You find time for HN. Me, I can find time for 20-60 min a day studying Japanese (of which 5-20 is in Anki). I also find time for 20-60 min a day playing go so ¯\_(ツ)_/¯
Fine, time AND energy. HN is entertainment. SR feels like work. When I have an hour at night on average to yourself, I don't want to spend it studying. I've tried taking breaks at work to do it, but you need those mini breaks at work to be a bit unproductive as well. I can't be "ON" 100% of the time, I need rest.
