No one is being mean nor nasty; in fact I started out with: "No disrespect, and you're certainly open to your own opinion..."
hCG keeps a mans testicles alive and healthy as it is an analog to LH. Men who use hCG, if Secondary Hypogonadal of course, will continue to produce some amount of natural Testosterone but usually never in the amounts needed to overcome their hypogonadal state...thus TRT.
So it's easy to deduct that hCG activates the P450 Side Chain Cleavage Enzyme, the same way LH does, which is primarily responsible for converting Cholesterol into Pregnenolone. (Oscar's post above.)
With HPTA suppression the Axis is not functioning and therefore LH and FSH production is pretty much halted...and for life...that's why many men at some point see Testicular atrophy without the use of hCG. It's also why LH and FSH assays are useless once a man starts a TRT protocol.
When a man introduces exogenous Testosterone in his body he stops producing natural Testosterone due to HPTA suppression. No matter what, the Pituitary will not start up and begin creating LH...it's impossible if a man continues with a TRT protocol. So to keep the mans testes alive and functioning properly the use of hCG is needed and as noted.
With TRT all the other hormones upstream of Testosterone are severely depleted - especially Pregnenolone and DHEA. These hormones are progenitors -- meaning they are the "Mother" for all other hormones
and have a say in all the other endocrine pathways not just the Androgen Pathway.
So it's vital to back fill the pathways by supplementing with both Pregnenolone and DHEA in sufficient amounts to make sure we are providing all other pathways with the needed basis which to function optimally...they do so much!
None of this has to with with LH which is the messenger hormone produced by the Pituitary gland which is suppressed when exogenous Testosterone is introduced into a mans body. The only way a man can make up for this short fall in LH production is by introducing an analog to LH which we all know as Human Chorionic Gonadotropin...and no amount of Preg or DHEA can change that...wish it would...hCG is a bit expensive
BTW, I didn't mean to come across disrespectful; so apologies if I did.
Peace out.