Probably because people who look for tutorials are not experts, so it's hard for them to tell if a tutorial is good or not.

Because a garbage tutorial isn't necessarily incorrect. The solution in the tutorial might be slow, inefficient, un-optimized, hacky, etc., but if it works when people have been slamming their head on the desk for hours, people will use it. It's a matter of which tutorial captured the audience first.

I think it is just numbers.

There are many more poor quality tutorials written than high quality tutorials because high quality tutorials are much harder to write.

The writer has to know the domain, be up-to-date in the domain, have the communication skills and the time to write and edit.

I can speak for "data science" tutorials: there's A LOT of people saying you don't actually need to know the math!

Learning math makes you feel stupid.

Because people find them using search engines optimised for popularity (not quality) of content, as perceived by the readers, not a community of experts.