Oh, its definitely indirect. Potentially a million things could cause redshift of light. Assuming it is expansion of space is a good assumption,
First, you are correct that there are a million things that could cause redshift, but 999,999 of those million things are going to be localized, and localized explanations for redshift do not explain the universal (and universally consistent) redshift that is being observed.
Second of all, expansion of space is not an explanation for the redshift we observe of individual galaxies. Those are just individual observations. And you're right. If redshift was observed sporadically, then there would be a million different explanations for what causes redshift in galaxies.
But it doesn't occur sporadically. Redshift is observed universally. As in, every distant galaxy that has been observed beyond our local group has been observed to be redshifted, and the amount of redshift each galaxy has been observed to experience is consistent with distance (galaxies that are further away experience more redshift). That's a dataset that numbers in the billions if not trillions. That kind of universal consistency across such a gigantic dataset demands a single universal explanation rather than 10 billion localized explanations, and the only universal explanation that has been found is the expansion (and acceleration) of spacetime.
So no, it's not a "misconception" that spacetime is expanding.
Also the astronomers now have a deep issue on their hands, as they don't get their different measurements of the Hubble Constant to match up with each other.
What you're talking about is a matter of scale, not direction. It's the climate change argument all over again: scientists might not agree on an exact value, but they all agree on the general direction and order of magnitude.