It's true that edtech hasn't (yet) created an educational utopia, as some people may have imagined or hoped. But there are educational technology tools that my son (8yo) uses several times per week, that undoubtedly help him to learn important stuff:
1. Math Academy (truly amazing for 4th grade math all the way to first year of undergrad: https://www.bit.ly/ma-way)
2. Skritter (for learning to write Chinese characters)
3. Anki (flashcard program).
4. Octostudio (for learning to code, by the same folks as MIT Scratch)
#1 and #2 are both much more efficient (learning per unit of time) than any other method I've seen. They (along with #3) use spaced repetition and retrieval practice as part of their secret sauce.
But they are also highly domain-specific. Math Academy relies on thousands of hand-crafted math problems, all designed within a (hand-crafted) graph of topics that students must master. Skritter has tools that give people (adults or children) an easy on-ramp to learning the broad strokes of each character, and more advanced modes that train more precision.