No it is not a fault of OOP, it is just that OOP does not really provide the tools to help either. It is the fault of people with the wrong expectations or of those trying to sell snake oil.

OOP allows to create decoupled systems but it doesn't help in creating them. It is not an inherent property of the paradigm, but many people sold it as such.

"Use OOP and your application is now magically more modular! Buy my latest book to find out how!"

Since you mentioned you are a junior I guess this sort of nonsense is from before your time. No worries, that just means you won't have stupid dogma shoved down your throat. Use whatever paradigm if it helps you and avoid whatever gets in the way.