I'm glad this article actually presents both sides. The latter paragraphs talk about another study in which THC did nothing to cell growth, and makes it pretty clear that the entire affair's still really uncertain. I don't think this shows up in many of the pro-marijuana (pseudo-)scientific articles on the web.
It would be great if I could read something like this without running into a comment in which someone describes it in terms of "sides".
This is not a debate. There are no sides.
There are just studies: one that found that particular chemicals assisted new cell growth in some parts of rat brains, and another that found that a different set of chemicals did not assist new cell growth in the brains of different rats.
It's interesting stuff. Trying to frame it in the limited context of a social debate really diminishes its value.