100% incorrect. First and foremost a lot of the stuff I watch is released under
the Creative Commons license. But irrespective of that downloading videos from YouTube can be 100% legal in the same way it's legal to record from your VM/Sky box anything being broadcasted for offline viewing (as long as you have a TV license) or even recording with an old school VCR. It's what you do with the content that makes it illegal. Creating a copy for offline viewing it's perfectly legal because I am not going to share it or upload it anywhere and I am only watching once and then deleting it. This is very different than with the music files use case discussed in your article. And for the record I don't use any of the named sites, I use local software on my computer.
You can get a better explanation as to why these sites were blocked from
this ISPreview article: "[...] block websites if they are found to heavily facilitate internet copyright infringement, which is supported via Section 97A of the Copyright, Designs and Patents Act [...]". None of what I do "heavily facilitate internet copyright infringement" since I don't upload, share or keep the content I download. And most of it is CCL anyway.
Patreon takes 8-12% (depending on the plan) plus payment processing, currency conversion and payout fees, and applicable taxes so say roughly 15%. That is far from "eating a fair chunk" and is certainly way more than what YouTube shares with creators (45%) or what you can make on merchandise. It also takes minutes to setup. Ad revenues are actually quite stable, spikes in viewingship are less common on well established channels which is what I watch.
Also the revenue share (based on CPM - Cost Per Thousand) is strongly linked to CTR (click-through rate). Since I never would click on an ad, anywhere, to discourage ads, even if I watched the ad in YouTube I wouldn't impact the CTR. Viewing impressions that don't generate clicks lower the CPM which hurts content creators as they get paid less. So you really need to understand how advertising works before making blanket statements saying "you are hurting content creators".