In many programming languages, initialization of local variables is forced, or the engine will flatly refuse to read uninitialized data. Even in languages where you can read uninitialized variables and thus get a copy of what remained in RAM at that emplacement, you cannot count on it to be "random"; it will have a tendency to contain always the same value, depending on what the application did previously. Indeed, in C, local variables are from the stack and/or cached in CPU registers, and these are resources which are constantly reused throughout the application.
If the article you read recommends not to initialize local variable, and then to read them, and expects this to yield "randomness", then this article shall be burnt to the stake, for many reasons:
Reading uninitialized data is a clear breach of specification; in the C programming language standard, this is called "undefined behaviour" and may yield problematic results, including an application crash, or, even worse, silent memory corruption.
This kind of randomness will not be any good, by any notion of "randomness" worth speaking of.
Reproducible behaviour is good. By trying to obtain non-reproducible values from local variables, the article just promotes making the code impossible to debug, which can only be described as a bloody stupid thing to do. In particular for security. This will almost guarantee the presence of long-standing, hard-to-detect security holes.
If you want randomness, use what the OS provides, e.g.
/dev/urandom. It is incomparably better, from all point of view, than irrational home-made rituals meant to propitiate the gods of randomness.
Edit: As @TerryChia points out, your question might be about forcing a random initialization of variables (local or not) from a PRNG, instead of leaving the default value there (if there is a default value, of course; in many programming languages, local variables have no default value at all). What you call "XOR" in that context is unclear.
In that case, either you do not read the said variables before storing a meaningful value in them, in which case what the variables initially contained is completely irrelevant: it does not impact the behaviour of your code. Or you do read the variables and then get these more-or-less random values from them, making the application code not reproducible and leading to the problems explained above; namely, that the code will be hard to debug, increasing the probability and density of actual vulnerabilities.