For years, wordpress stored user session data in 'wp_options'. Moderately trafficked sites needed to come up with regular purging hacks to 'clean' their wp_options table. Why? Session data is not an 'option', it's... session data. Make a database table called 'wp_sessions'. Transient 'cached' data also... in 'wp_options'. This was not an example of 'good engineering'.
This is just one of many examples of suboptimal tech decisions. Some have been mitigated, updated or otherwise 'fixed' over the years, so they may not be relevant any longer. It's a very popular and widely used platform despite some poor development and engineering choices, and perhaps even in some cases because of these poor choices, but that doesn't make them good engineering.
The idea that no one is allowed to criticize anything unless they can and have done better is one of the most perniciously stupid ideas out there that just won't go away.
If the parent poster is secretly Linus Torvalds, do you walk away in shame because he HAS done a project with better engineering? Or are the criticisms, perhaps, objectively valid or invalid, and worth engaging with regardless of the merits of the person making the criticisms?
Well when their whole argument boils down to "php sucks" and they back up their claims with a document that was invalid 12 years ago when it was written, they better have something to back up these criticism.
Perhaps you should engage with the claims rather than the person. As someone who doesn't frequently use PHP, the criticisms in the linked post from 2012 seem valid if the facts presented are true -- there's some pretty weird, and in a few cases, downright dangerous behavior presented there.
What is invalid, specifically, about that blog post?
