Proprietary dev framework built on proprietary 4GL
As they used to call them back in the day.
A number of companies built successful businesses on their in house dev language and tools (like MDIS building the software most British libraries ran on).
And conceptually I also like the idea of a large organization in house IT being able to say to any of it's OS vendors "F**k you. We're off this platform. You're history"
But betting on Google to notdump this in X years, where X is a quite small integer?
As for "performance" the wrong answer produced 100x faster than an accurate answer is still a s**t answer.