are they actually independent, or do they depend on someone else for that monetary/technical/marketing support.
People don’t look at that because that’s not a useful metric. All the big publishers have their own studios so most things they publish are ‘independent’ by that definition, but they are the very thing people try to exclude when they say indie. In the indie definitions of both music and films, it is stated that they are independent from the established distributors, not that they are entirely self-distributed. It’s unreasonable to expect that from indie games.
And conversely for ‘independent’ to have any meaning it mustn’t include those who are in a position where others could depend on them whether through money, name recognition or some other thing. CDPR for instance, by the merit of being very well known and owning one of the most popular online stores is absolutely not an independent studio.
Edit: furthermore even when a large distributor is involved for marketing etc, this doesn’t mean the production of the art can’t still be largely independent.