It was based on a similar story the one in OPs blogpost. At my first job I used to work with some really talented fresh grads that wanted to show off their algorithms skills and ended up over-engineering stuff.
One of them implemented a trie and stored it in SQL lite to implement some string autocomplete where the number of strings was something like 100.
The other implemented a 2D segment tree for doing some grid updates where the size of the grid was small. This inspired the first part of the meme. Segment trees and sqrt decomposition are topics that are popular at programming contests and nowhere else really.
Regarding the triple nested loop, I just wrote the simplest pseudocode that represents nested loops, not necessarily something a "senior" developer would write.