I'd rephrase: "excellent compromise"
It's a reasonably accurate solution, that avoids major effort and expense. No purchase of 8 or 16 flow sensors (and the ones made to be outside are expensive). No installation of 2 or 3 conductor made-for-underground cable to each flow sensor (a lot of work; serves as antenna to bring in bad surges to Rachio).
And with you guys being a s/w company, this should be a lot easier than a h/w solution.
This is simply incorporating 'in Rachio' what I outlined a few days ago 'outside of Rachio.' My outside of Rachio solution is about $600 - my guess you guys can do it 'in Rachio' for much less.