> If I saw that code at my company, I'd ask why someone building a rest api for web-services had to iterate through a 10000*10000 2D array while calling a method of every single cell

Why not? I work with the scripting languages only and regularly hit this scenario so I won't say this is completely useless.

When you analyze a few hundred 50GB files for specific patterns, you have to go line by line in those cases shaving off milliseconds, optimizing how data should be accessed and optimized becomes valuable.