The purpose of HGH is to increase cell production for a faster recovery. The problem is that HGH not only increases "good" cell production but also "bad" cell production (i.e. cancer cells).
There is a whole lot of misinformation about HGH. The Wikipedia article links to several research articles, which I took the time to track down only to find that they were misciting and misrepresenting their sources (this is why you can't just blindly accept what Wikipedia says even if it does have a reference). It turns out that there is really no evidence at all that HGH speeds up recovery, or does much of anything at all to improve your performance, unless (a) you are HGH-deficient like an extraordinarily small subsection of the population, (b) you run track (it makes you a
tiny bit faster, enough to matter in elite-level athletics but not enough otherwise), or (c) you're taking it in combination with steroids. "Then why do players do it?" you might ask. Well, players do a
lot of things that don't make sense if they think it gives them an edge. Pop greenies, cork their bats, go through a particular ritual before each at-bat, not change their clothes or shave their beards... anything for a perceived advantage, however slight. The fact that HGH is a medical substance with "growth" in its name makes it even more alluring.