It's a fact of life that software gains new features, and that system s/w people cannot continue to support old services that lack these features. You wouldn't want it any other way; it'd be impossibly expensive to test that all the old services are compatible with new ones.
It's a fair question whether Apple gave developers sufficient advance notice of these changes, but it doesn't seem you have any info to say yes or no. Above, a Canon person says they have stopped trying to maintain MX922 support; a Canon rep I spoke to said the opposite. Until we have a clear statement about Canon's ability to work on modern OSX, it's churlish to say it's an Apple error. And it's unhelpful as it just gives up in resignation until Canon can clearly state their intent
