I'm working on a large (at least 300k+ loc) Django code base right now and we have 32 direct dependencies. Mostly stuff like lxml, pillow and pandas. It's very easy to use all the nice Django libs out there but you don't have to.
I was talking about total deps, not direct. By installing something like Celery, you get 8-10 extra dependencies that, in turn, can also have extra deps. And yeah, extra deps can conflict with each other as well.
That is obviously true but doesn't mean as much as you seem to think. Washing laundry is also not much work but it adds up to a lot over the years, especially if you skip a few weeks of laundry every once in a while. That is not an excuse to not do it.
The answer is the same in both cases: acquire some discipline and treat maintenance with the respect it deserves.
It is easy, and people tend to do what is easy. It takes more effort to minimise dependencies. Your boss or your client will not even notice.
Obviously there are some dependencies that you cannot easily avoid (like the things you mention). On the other hand there is a lot off stuff used that is not that hard to avoid - things like wrappers for REST APIs are often not really necessary.