Visualize how much junk from third-party sites you download when you visit your favorite web site: https://simonhearne.com/2015/find-third-party-assets/
Mathstodon.xyz: Completely clean. Wikipedia: only a few small bits and pieces from other Wikimedia sites. Some other sites that I visit regularly: lots of junk. Adblockers help, but attention to keeping things slim in site design would help more.