Every kitchen has a knife.
You can use it to poke out someone’s eye, to cut your veins, to damage your household.
Why you’re allowed to have it at home is because a basic knowledge of its use is assumed.
If given basic security training in PHP via the resources linked in the original article, one becomes basically proficient in PHP security measures.
Much like you don’t let a child stab itself to find out knives are dangerous, so shouldn’t you let a rookie developer sabotage themselves with bad, outdated resources. As a PHP developer, it is on you not only to develop, but to educate those around you and to help spread good practices by means of, at the very least, referring them to proper sources.
Like the others said - every language is as insecure as those using it make it.