If a DE has a list of "must install" extensions/plugins for it to be usable, then that DE is not for me.
I don't know most of these extensions, but from the names it very opinionated and depends on who you are if those extensions are a must have for you. I mean, Burn My Windows does not sound like a must have, while Caffeine does.
Title should have been: "15 Extensions I Have To Install On GNOME".
You can disable the screensaver and auto-suspend just fine in the settings, caffeine lets you toggle it from the panel, I'd hardly call that a must have, if anything it'd annoy most users who prefer a clean panel.
I prefer the gnome approach of having a functioning basic DE where you can optionally install extensions that you want.
It's "usable" but nobody is going to use it every day without wanting any number of things you need an extension for, which is a pain, and does make Gnome look user-hostile compared to KDE