Website applications that require an intervention from user side, are not considered worth it.

User will not waste their time, or clean cookies or install an additional extension, library or whatever just to make a single app work in their browser.

That is a problem of the programmer to have all pre-requirements set, instead making a half-ass product.

So, whatever requires a special treatment to work isn't worth spit.

Always build CLEAN apps with all the things in place.

Always BETA test it.

Make sure you have the latest libraries securely hosted.

Host independent files, APIs and don't rely on third-party as much as possible.