But if clients were considerate, we wouldn't need to waste electricity and work hours to run CDNs?

You would want a CDN anyway to cache data across users, on servers close to those users, cutting the time & energy spent to serve the data.

I feel like this is a marketing meme by cdn providers that gets parroted a lot. As someone who has used CDNs vs hosting on the server directly, CDNs are slower to load the images especially when there is a cache miss. The only reason I’m using a cdn is because I need to host 100gb+ images. If it wasn’t for that I wouldn’t use a cdn and get a better experience on the site.

  >In this case, [X] would improve things more quickly than [Y].

Maybe so, but more importantly why are you phrasing this like it's an either/or choice?

"We, the developer community, contain multitudes." Clearly we can (and should) do both.

Besides the obvious benefits at the higher community level of organization, deploying both solutions will result in even less bandwidth and power wasted from this specific bug than using either solution by itself.