Earlier quoted context omitted.
You could take “C#” out of that sentence and still be accurate. Wordpress is not and I imagine never will be anywhere close to “modern design patterns”. It’s not even close to old design patterns, unless Heinz has a namesake software design pattern. Wordpress uses practices that were considered a bad idea a decade or more ago, and still refuses to change.
Then perhaps, in true open source fashion, you can put your time where your opinions are and either start another project or help the wordpress team to correct what you think is bad.
But, in response to your general theory: I can criticise a car as being fucking terrible without someone suggesting I “go build my own then”.