The one thing you missed is that plenty of teachers won't spend the 15 minutes. The first time an edtech feature doesn't work in their classroom - usually because the teacher is using it completely incompetently - they just stop using it altogether. It took the school almost a semester just to get an english teacher to stop making the students use paper notebooks because she resented the tech so badly.
And you can see where the resentment comes from - lots of teachers do NOT tend towards technical literacy. A lot of them are older and underpaid, and they aren't going home and plugging away familiarizing themselves with contemporary tech to "skill up." The reason "kids can't use computers" is no doubt because plenty of their teachers can't either.
I'm just offering up a possible reason that someone wouldn't want to learn. I strongly believe that most of the current "hate on learning new computer systems" is due to programmers and designers more than cranky users
Bad educational technology can get in the way of teaching and learning. Errors/bugs and confusing UX can cause lengthy delays in the classroom.
Teachers can easily spend 15 minutes running around playing IT support when students are using a new technology – out of a 50 minute class which was scheduled in 5-minute increments.
That doesn't mean it needs to be "beautiful, seamless" software like we tend to idolize. Or the most featureful or innovative. It can be, but getting bog-standard basics working without confusion or errors is far more important. I certainly agree with the author on that.
(Source: previously cofounded an edtech startup, spent time in many classrooms observing these things).