You wouldn't have to write if(a==a) in the first place in those languages, however. if(a) would suffice in C and C++ for an integer type or a pointer, and possibly for an object in C++. An integer value would also work in Python. I can't say anything about Ruby.

The fact that a==a can return false isn't really the main criticism here. You could override the == operator in C++ to do that too. The article is claiming that having a literal boolean true be the only "true" value is an issue. I think I agree with this just because this code evaluating to false is out of line with every other language out there, and I haven't seen a case (yet?) that it's an improvement for any other practical purposes:

  a = 1;
  if(a) {
    print("A is true!");
  }