I think your graph is accurate when it comes to the amount of effort put into polishing each language -- but as to actual quality, I'd firstly say y=1 is the go

I think your graph is accurate when it comes to the amount of effort put into polishing each language -- but as to actual quality, I'd firstly say y=1 is the goal (the language is basically complete; you can add more around the edges, but the core is solid and needs no more changes), and it doesn't account for the fact that with a constant large amount of effort as input, progress as output slows down exponentially due to backwards compatibility concerns. As such, I still think that starting off good and evolving slowly is better than starting off awful and rapidly turning into a giant blob of band-aids :P Again with the scales, I agree that PHP is great for getting things done to start with, and once you've started with something then carrying on using it is easier than changing. That's why my biggest and most successful project still uses PHP, even though experience has taught me that everything else is more productive after the initial setup hurdle~ Stability, agility, and testability have been in other languages for decades, and in all three cases other languages have done them better, so I'm not sure why PHP having them since 2005 is supposed to be a good sign...