> Alexa, Siri, Ok Google

Complex digital assistants aiming to be do-everything secretaries are not what I had in mind when I said "simple algorithmic approaches".

That aside, which of those were attempts to improve input to a computer like the project submitted here? Everything you listed was most focused on (a) trying to establish voice as a valid input method (b) to create a new class of applications (c) for more-or-less locked down devices. (The one assistant that's closest to what I'm referring to—but still misses the mark—is the one you didn't mention: Cortana.)

> because every type of action required a handcrafted integration, they were either costly to develop or extremely limited

That describes all conventional software—think of everything you do on your computer. How many lines of code across how many different software packages, each handcrafted, are on your computer? And how narrow versus broad and featureful is each one (calc.exe, for example)? "Do one thing and do it well" is an entire, night regarded philosophical outlook about how to make great software.