The more time anyone spends with WordPress and all associated products (that is, themes, plugins, and so on), the more likely they are to also pick up on all of the commentary – both good, bad, and neutral – that surrounds the core application.
Obviously, I’m a fan of WordPress and make my living building things for it and trying to give back to the core application when I can so I know that what I’m going to say is going to come off as biased just as anyone else who writes about their preferred technology stack.
I’m well aware of the common complaints people have about the WordPress codebase and I’m not here to defend, to make statements about how it’s getting better, or to spark a discussion on how hard it is to maintain legacy features for a decade.
But if you’re a developer who is just getting into WordPress – specifically, products built on top of it – then I think that a significant portion of your first impression has to do with your experience on the first product that you use.