first of all i don't think its the same for all artists but if it happens organically then it happens, and that means it's an emergent feature - like all things that just HAPPEN! logically it follows that “pursuing a personal distinct style as a priority" may not the best use of an artists time.

"that artists may try to alter their natural personal style" im not so convinced such a thing exists.. a "natural style", these two words may actually be in contradiction even - style is when something is done in a particular way, when it serves particular visual principles and also has unity and self consistency.
when in a "natural" state one has no principles, no particular way of doing etc. someone draws something and it HAPPENS to look a certain way, usually more as a result of their inability to express what they are looking at or imagining. you may look at it and say "interesting style" but i assure you no style is there ((: its even sadder when artists embrace these limitations, that we all have, and say something along the lines of "thats my style, im more of a bla bla bla" - and that woo woo may work on a your average joe but for someone who is initiated will see right through it. and you know why?? turns out visual art is not an infinite territory, we all make the same mistakes more or less when learning, we all try to "cover them up" in similar ways etc, the path to being an good artist is not very different for people, they practice a lot and make a lot of errors on the way, and thats normal.
so in conclusion cause this turned out to be a really long reply :)) if by natural style you mean bad, uneducated, random results then yes there is such a thing (:
if you mean something deeper, like a predisposition pattern for a style then that has to be nurtured by practice & experiment.
so its not nature, its nurture (:
thanks for commenting, have a good one!