Are Behavior Trees a must have or can complex AI be done entirely in C++

Hello, I am creating a soulslike game and struggle to implement Behavior Trees for my enemies. I already have pretty simple AI done entirely in C++ that can patroll chase and do a simple attack.
I wanted to switch to behavior trees with tasks in C++, because i figured that it will be better for more complex AI behavior. However i find it very hard to implement and feel more comfortable with only C++. I struggle with controlling blackboard variables and generally my game is way worse off right now.
So my question is: Is it worth to keep learning about behavior trees because it will pay off when AI system will be more complex or can i just write more complex C++. I am worried that Behavior Trees are considered industry standard and i will end up with endless lines of code that are hard to debug.
What’s more i can not really find a lot of ressources about implementation of Behavior Trees with C++ so i am not sure are BT so popular after all.
Thanks for Help

You already said it yourself. When you want to make a complex AI and it needs to be extensible it is almost certain that your own code will not suffice. Using an existing framework is difficult at first unlike the stuff you made yourself but in the long run it will be worth it.