@Tbayer (WMF), I just read your comment at phab:T200794. It looks like making these banners more visible increased the number of people reading them during the four-week study, but it decreased the number of people editing the article by ~5% at the English Wikipedia.
Will you be watching this long-term? It is not unusual with a UI change for everyone to click on it once or twice to figure out what it is, and then to ignore it afterwards. Consider, e.g, Facebook when added links to Wikipedia articles about the newspapers to their news feed. Everyone expected a spike in page views, but my spot check indicates that the October 2018 page views for those articles seem to be the same (or even slightly lower) as the October 2017 page views. The spike came – and went.
So what we've got now is a ~4x increase in reading the banner, when the banner was newly visible, but will that increased rate be sustained, or is that a temporary spike that appeared and then left?
This matters. The communities could decide that 5% fewer edits is okay, if 1% of readers are getting more information about how Wikipedia works. That could be a lose-win combination that we decide to accept as a tradeoff.
But if that 1% drops back down to the previous miniscule level, then we're left with (1) fewer editors, (2) no additional information, *and* (3) a more cluttered interface. That sounds like a lose-lose-lose result.
 It is not hard to hypothesize a mechanism for this: "Oh, look, they already know about this problem. I don't need to fix it, then."