Because some things are done for learning exercises and nothing more.
Just because that code isn't going to do anything useful when executed, it does not mean that there is no value in the exercise of producing or sharing the code.
Not that it needs that much justification, fun is a good enough reason.
* I have no problems with 'fun projects'. I do them myself.
* I have no problem with 'useless code'. Many fun projects are never useful. I have done these myself.
* I have no problem with learning for learning's sake. I have engaged in lots of that.
What I don't agree with is artificially limiting your project's potential. By choosing to implement brainfuck, instead of Tcl or Lua or Forth or Lisp or any number of other languages (even if it's just a toy version, and not the full spec), you've consigned your project to the dustbin before you've even finished it. To my way of thinking, that just doesn't make any sense. If you want to be artistic, go out and make your own language.
Even a simple language like Hecl is used for real things in the real world, something I wouldn't have imagined when I started writing it. An implementation of Brainfuck will never be used for anything more than learning.
Which continues to be my point: learning's great, but why not learn and do something that has a tiny chance of developing into something big?
What about the people that study klingon? Or Esperanto? Or Elvish?
You assume that a person cannot gain something by simply learning something that has no practical purpose. This isn't the case. By working on BF, someone might make some neuron connections that help them with logical thought with other projects, by breaking down logical thinking into very simplistic, basic symbols--completely removing "language" out of the equation.
You just don't know. :P
"Elvish" doesn't actually exist. There's Quenya, or 'high' elvish and Sindarin, 'low' or 'gray' elvish.
cough
Carry on!
Actually, what I wrote, if you'd bother to read it, is: "Yeah, he learned something for sure, but that's pretty much all it can be." so don't put words into my mouth.
The point boils down to this:
* It'll probably never become big.
* That doesn't really matter, it's mostly for learning and for fun.
* But even so, why preclude that? <- this is all that is causing people to get their knickers in a knot over what I wrote.
> You're assuming that every thing that people work on actually needs the potential to become "big".
If you get that essentially for free, then why the hell not?