They do it because C++ tempts you to strive for perfect expressive syntax and perfect efficiency at the same time. Most languages have limited expressive power

They do it because C++ tempts you to strive for perfect expressive syntax and perfect efficiency at the same time. Most languages have limited expressive power (C, Fortran, Pascal) or limited efficiency (Haskell, ML, any JVM or scripting language), so you accept their limitations and move on. C++ makes programmers become Icarus. Once they escape from the prison of C syntax, they try to fly higher, towards the goal of code that looks like Python but runs like C. They learn that template metaprogramming can help acieve this goal, so they use it. But template metaprogramming is actually the sun, melting their code into a pile of wax and feathers, sending them crashing back down into the ocean to drown.