I agree that the learning curve for tikz and latex is greater than word. However I think it is disingenious to say that tikz and latex are no different when it comes to the initial and/or MWE learning curve. In my opinion tikz's learning curve is steeper. For starters there is no tikz equivalent of:
Pandoc drastically reduces the initial learning curve for latex and beamer.
That being said tikz was one of the packages I thought was noticeably absent from the nine listed packages. The other package that I would add was fontspec, in fact I was shocked to see microtype and not see fontspec mentioned next.
That's a fair assessment. I drank the LaTeX koolaid >15 years ago when I didn't even have a clearly compelling reason to do so. Now back in school working on a PhD, and wondering why anyone wouldn't use it. How quickly we forget our learning pains.
TikZ is not different that LaTeX in general. It has a hard learning curve, but you gain long term on reuse, structure, versioning.
Also slides in Beamer are a mess at the beginning, but maintaining/sharing/co-working... I personally think it's way easier than with ppt.