While parent's comment seems to attract some downvotes, there is a good point hidden beneath: PHP (mostly) keeps backward compatibility. This means that old and

While parent's comment seems to attract some downvotes, there is a good point hidden beneath: PHP (mostly) keeps backward compatibility. This means that old and unsafe functions that should not be used anymore are not removed from the language and are still available to use. Coupled with a lot of outdated documentation and tutorials that advocate using these functions, it becomes a big issue. For example, many tutorials use "==" when "===" should be the default. Deprecated functions are used in many tutorials as well.