Did you actually read the article you posted? It states that 79% of sites are using PHP. WordPress is 40%, Joomla 2%, Drupal 1%. So no, they don't combine to ~90% of PHP sites, far from it!
The article even concludes with:
"PHP is far from dead, no matter what any disgruntled developer may tell you. After all, 79.2% of all websites in the world can’t all be wrong, and most importantly, PHP’s market share has remained relatively steady throughout the last five years (oscillating between 78–80%). Few programming languages command that type of staying power."
PHP powers a lot of legacy code bases, yes. But there are also a lot of job opportunities in Laravel and Symfony which are both very good frameworks.
The article even concludes with: "PHP is far from dead, no matter what any disgruntled developer may tell you. After all, 79.2% of all websites in the world can’t all be wrong, and most importantly, PHP’s market share has remained relatively steady throughout the last five years (oscillating between 78–80%). Few programming languages command that type of staying power."
PHP powers a lot of legacy code bases, yes. But there are also a lot of job opportunities in Laravel and Symfony which are both very good frameworks.