Because John experiments with X for the first time and writes about it on his blog. Janette has the same problem while learning about X so she takes his code, makes a few changes and puts it on her blog. This scenario happens 8 more times and we have 10 low quality tutorials about how to do things, but none of the authors has experience and expertise in X, and they won't admit it. Bad practice is copied to many places. 1000 garbage kill 1 gold.

Non experts look for tutorials,

They chance upon tutorials by non-experts

They don't know enough to tell they're junk

They use the code, link to, and suggest those tutorials to others

Those tutorials are getting higher ranks, attracting even more non-experts

There's your problem. If you are writing a "here's how I did it" post, you should be clear that you don't have any idea what you're doing.

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.

Learning math makes you feel stupid.