Suppose I want to debug memcached usage in MediaWiki. I look at MemcachedPeclBagOStuff.php and see that it is calling $this->debugLog() with what looks like useful debugging data. I want to get that data. How do I know where it is going and how to configure it? Previously, the log channel was right there. Now I have to hunt down the constructor, which isn't always easy. Grepping for 'new MemcachedPeclBagOStuff' won't find it.
@bd808 suggests that we simply "ditch our weird habit of arbitrary log channel names and instead make them all match the class name except for 'exceptional' log channels". I think it's a great idea.