The problem is, my friend, you are encumbered by your own knowledge. We're not all developers, so don't understand the whole process anywhere near as well as you, and for me at least, there are great big holes in that explanation.
Immediately I am thinking about, how should my DNS and Webinoly be set up to create this dev. subdomain, and what about the SSL and wildcard certificate installation. From my own experience of trying to use the clone function on a production site, there's a planning stage and correct order of events which your "one-minute tutorial" doesn't touch on.
But yes, for the simple use-case where you simply want to create a site (whether awesome or not) and show/deliver it to your client, as a top-down view, that's fine.
However, that only explains "cloning" in principle; and not the entire process of using a "staging" site on an ongoing basis. I see them as two parts of the same process, but not the same thing.
For example, your explanation doesn't (wasn't intended to) cover the steps needed and processes for maintenance and updates, especially where it relates to a transactional website using WooCommerce, where you have live transactional changes occurring daily, and you might want to make ongoing design or update changes on the "staging" site, and then move them to the "production" site, when they all check out.
In that scenario there's a fair bit more to be done with backups, Webinoly and DNS management, right?
To give something back, if I wrote such a how-to, in the style of your "Webinoly full example and tutorial", and contributed it to the project for use (or not) as you see fit, would you help me where I get stuck?
It would be helpful to me and help put my thoughts in order, plus I am sure I will learn a lot along the way.