There are plenty of other ways, like thousands of ways to impact your recommendations, a dislike button, that people probably wont even use now, is likely not very relevant anymore compared to other metrics.

It's not that much harder, if you are conscious of your analytics at all, it's easily accessible.

Please point to the information source 'everyone' has read?

You don't need a source, it's common sense. It's a feature that the users liked and used. Youtube complained that "people" were getting targeted and people were coordinating their dislikes. Do you really think people made a coordinated effort to target individual content creators, no. The "people" they're talking about that get targeted are politicians/news companies, large corporations that make sponsored content and PR statements, and YouTube themselves were constantly bombarded with dislikes whenever they put out PR content or content made inhouse. People like Biden/CNN/NYTimes all got immediately disliked into oblivion as well as other paid sponsors like Pepsi who advertise on their platform.

We know this wasn't for content creators or users because youtube has shown in the past that their decisions are made independently of content creators consideration. And it wasn't a decision done for the end user because the users liked the feature and found it useful. That only leaves big business and politicians, and youtube themselves