I wish WM
Okay, here's the gen - I don't think it's meant to be any secret.
No. Unfortunately all sites are open to spammers, who load their computers to scan open sites and auto-submit membership details. You can try to slow them down with things like we have here, the 'captchka' (that's probably the wrong spelling), whereby you have to type in 'what's in the box' before you get past screening.
But the serious spammers bypass that and appear as 'latest member' all the time.
What happens is, we as mods are alerted by email every time someone joins the site. At that point they are automatically designated 'inactive members'. We (mods) then go to the long list of recent, new, Inactive Members, scroll down and look at the names, which are invariably gibberish (or obvious site names), and delete them.
If we didn't bother to delete them, nothing would happen, since we do have to 'activate' members before they can post. But it does lead to rather huge lists
If we instead 'activate' rather than delete, then every post, on every board, would be subject to the kind of posts we would all (I hope) really rather not see
Some of these auto-spammers are for gambling sites - bad but not awful - but a lot would lead to far more dubious websites and of course probably viruses etc.
As to turning people away, nice thought, but no, no-one would know we are here unless a current member passed on the site details. We would love to have more members, but in reality are reliant on present members recruiting new ones