"I don't actually agree with this. It's a cop-out. Some people will just say "Well, this procedural mess I've been copy-pasting since 1996 works for me, so I'll keep using that. Make an informed decision about what's the best option. That may or may not be to learn a new technology. But don't take "works for you" to mean you should not bother to progress in your learning. Too many PHP programmers sit back and stagnate."There is always an exception to any rules or advises given. It's considered a best modern practice to write you web application using a framework rather than flat PHP script. However, taking into consideration of the talent and time available, sadly you have to live with the flat PHP approach.
There is nothing wrong with that provided that you don't have to maintain the code base. If you're stuck maintaining the legacy stuff which will slowly hinder your learning progress, career advancement, and suffer the consequences of technical debts made by others, you're left with four choices. Put up and shut up, rewrite it using modern approach, delegate to another developer and never touch it again, or lastly just move on.