So where is the link to the page which has the how-to on all the things a noob has to do to make his DirectAdmin install safe, optimised and capable of building a successful hosting business on?
LoL. I don't know of that name. DA is easy to install and cPanel will probably also have a kindlike name. But surely it's not intended for newby's. It seems logical that people who want to start being a sysadmin have already a basic OS knowledge and know some about services.
So no, there is no easy how-to install, secure, optimise and start a successfull hosting business howto for any panel, not for directadmin either.
The help section you point to, is part of security, but you have also to know and learn from the forums. For example in point 14 of that help file do not use that command for perl or you can get into troubles with addons.
never mind it was the longest and most complicated install script I have ever seen, anywhere on the planet
You haven't seen cPanel then yet. Takes longer.
And have you taken a look in the help section? If you do a search for letsencrypt you will find a lot about it.
As for security, DA is the only panle which has CSF/LFD now build in by default during installation, working with it's internal brute force business.
Really, if you want to be a wannebe sysadmin without knowledge, pay the price and use a cPanel license. And even then you won't be safe for everything by default and still have to configure autossl.
Want to be a successfull hosting business? Start reading the forums, more of the helpfiles. You don't have something like SSL? It's very easy to install, but you have to look in the help section.
There is also a newer help section, don't know the name.
It's quite easy to be done, but without basic knowledge? No there is no "how do I get from noob to hosting business install faq", sorry.