I think you don't find many problems because you're using firebase and that's outsourcing a lot of problems you'd face if you weren't using it.
Many people don't want to be tied to a provider to this level (I think it's all about trade offs, not saying it is a good or bad thing).
In the stack you described, in my experience, it is a real headache to get a stable and realiable system where you need authentication, permissions, users management, a CMS, background jobs, input validation, migrations, internationalization, etc.
Ruby on rails, Laravel, Django, etc provide a clean, well documented and battle tested solution to all of this. The modern stack you describe, if not outsourcing all of this to a third party, it is pretty complicated and no one builds it the same way.
That's why people complain about these modern stacks being complicated, you're just not feeling it because of the trade offs you've made. (Good for you!).
Many people don't want to be tied to a provider to this level (I think it's all about trade offs, not saying it is a good or bad thing).
In the stack you described, in my experience, it is a real headache to get a stable and realiable system where you need authentication, permissions, users management, a CMS, background jobs, input validation, migrations, internationalization, etc.
Ruby on rails, Laravel, Django, etc provide a clean, well documented and battle tested solution to all of this. The modern stack you describe, if not outsourcing all of this to a third party, it is pretty complicated and no one builds it the same way.
That's why people complain about these modern stacks being complicated, you're just not feeling it because of the trade offs you've made. (Good for you!).