I don't know how you would see the evidence of the company imposing their will on the project - that's not likely to happen in public. It's also very likely to happen without any explicit influence taking place at all.
If a company hired me to work full-time on one of my projects, and I had to pick between two competing priorities for my time, I would naturally take my employer's own preferences and current challenges into account when making that decision. I wouldn't even consider that to be a bad thing.
The problem with money translating to power is not unique to this arrangement, in any case. Donations can be similarly withdrawn, after all, so they also create an implicit bias. The only way to fix this is to make it so that people don't have to rely on such sources of income to sustain themselves.
Contributing improvements externally allows the project to remain independent. And if the maintainer is overburdened they can decline the patches or postpone review. Nobody is forcing them to accept the changes.