Hmm. I don't quite agree with that.
Here, let me show you what I mean:
aside from the posts in THIS thread (ironically), when I did a search for INSTALL PLUGIN, I didn't come up with too much helpful info.
Also, in regards to the thing that said "HOW TO INSTALL PLUGINS" on the front page that you enclosed in the red-box outline...
I think I know why I overlooked that.
Right above that, was the larger title, "PLUGINS -PUBLISHING ONLY".
To me, that implied that was a forum for people to go into if they were designing their own plugins and wanted to discuss programming with one another.
It didn't seem like the place where I'd go to learn how to install plugins (which ought be far more rudimentary than creating plugins) so I tried looking in more basic sections like GENERAL-FAQ.
Ergo, instinctively, I didn't read the secondary-title for that forum, either.
And besides...
If basic info for "how to install a plugin" doesn't appear from the forum-search, 'install plugin', that ought be considered a shortcoming that should be rectified.