Before we started using SRS I tried to sell my students on it with a heartfelt, over-prepared 20 minute presentation on how it works and the superpowers to be gained from it. It might have been a waste of time. It might have changed someone's life. Hard to say.

I'm less skeptical. You say that you got a few students to use Anki which, while probably not life-changing, is probably significantly life-impacting. If my tenth grade English teacher had introduced Anki to me... well, right now, I'm reteaching myself introductory biology (5 on the AP exam), introductory chemistry (5 on the AP exam) and introductory psychology (A in the college course) because I forgot the content of each of these courses because I lacked Anki. I obviously don't know everything you do in your classroom, but it's entirely plausible that, rather than being a waste of time, introducing your students to Anki might have been (on average) the most impactful 20 minutes of teaching you did all year; you just may not see all the benefit in your classroom.