Thank you so much for the feedback! Let me address your points one by one:
Some common examples of Type-1 Hypervisors are Microsoft Hyper-V, Intel/Linux Xen, and VMWare ESXi. I did not want to gloss over VMs too much as, in and of itself, it's a topic worth its own article.
The Dockerfile and a lot more topics related to the hands-on aspects of building and running containers are in Part two of this guide!
I did mention fully private Docker Registries when linking to the Registry's image. Most commercial options are still based on Docker's Registry image!
Also, to mention the meme/GIF comment, I understand your point. The goal of this article is less to be a guide and more to spark a little bit of interest in a Docker newbie. In my experience, a lot of the entry-level courses are dry, unrelatable, and tend to scare away beginners, making them believe that these are topics way out of their league.
If I, as a barely-average tech person, can explain them in a fun, relatable way, be it through the use of hand-drawn GIFs or a meme that might be stuck in your head, that barrier might be seen as less impassable, and new Docker users might start to understand the other, much more professional and structured guides and tutorials.
That is my take on using less-than-professional visualizations in an otherwise technical article, and I hope that you might see the benefit as I am striving to pass it along :)