The like/dislike ratio used to be a very good way to quickly see if the person who made it knew what they were talking about.
Now I instead have to spend a bunch of time reading through the comments to make that determination.
Not that bad DIY videos are useless. They can be a good way of reading a lot of comments on not how to do things. So they have their place. But I want to know that going in.
https://www.youtube.com/@futureunity5129/videos
Sort by "Popular" and you'll see that their most watched videos have consistently low like/dislike ratios yet are still being actively recommended. If you use Youtube's search feature, these same channels and videos will come up long before the actually informative channels do.
You could argue it's been helping Youtube by wasting viewer's time and making them watch extra ads but its certainly not helping the viewers find what they're looking for. Even mass reporting the channels doesn't seem to stop them.
YouTube is plagued by low quality content with clickbait titles, descriptions, and images. Often they outright lie about the content. The recommendation algorithm prioritizes these videos first.
Users can't determine in advance that these videos are poor quality, so they'll be forced to watch those poor quality videos until they find a good one. YouTube wants it to be like this because it increases time on the platform and their advertising revenue.
Along the way, users can dislike these videos but that video still gains views which helps push itself upwards in the recommendation algorithm. Particularly videos with clickbait titles, descriptions, and images tend to amass large numbers of views in short periods of time, which YouTube may recognize as "going viral" and give it an additional push in its recommendations when searching for important keywords.
Furthermore, many users are also watching these videos whilst not logged in or don't care to click dislike, which is another lacking signal to help tune YouTube's ranking algorithm correctly.