First if of all how would giving media companies more control fix the problems you listed?
And secondly why are you concerned about party affiliation with regards to this topic? I feel like you're looking for an excuse to disagree with people on a different part of the political spectrum. In my mind this is a bi-partisan issue.
There are very few people that benefit from removing net neutrality. I can list them here. The largest media companies, their investors, their employees, their CEO's and anyone in the government who is taking donations from said media companies. Everyone else should be very interested in keeping the internet relatively open.
I agree with you that many of the larger platforms on the internet have become walled gardens with a lot of content control and that is by design and by customer demand. The solution to this of course is to keep it open so that smaller niche sites can operate as alternatives. This has been the case as you can find many places outside of the main stream internet to consume media and distribute media of any kind (even illegal kinds).
There should be a balance here. Large media companies are easily manipulated and carry enormous influence. Giving them absolute control is not a good idea. I guess I just don't see what your argument for not supporting net neutrality is. It doesn't make sense to me.
EDIT
BTW: The reason companies like google, amazon, facebook and microsoft have so much power is that they own the software/hardware. It has very little to due with net neutrality. Net neutrality just keeps the ISP's from raining on their parade and taking control away from the tech companies.
In my mind what needs to happen, and is slowly happening, is distributed storage and computing power needs to take a larger hold of the internet. Combine that with open source software and you have a recipe for public control over a shared resource. For example, currently you are using a computer who's hard drive may not be full and processing power may be only partially used. It is connected to the internet and capable of doing work. You should be able to let others use it for a small price if you desire. This tech is years away but it's being worked on.
The internet is not complete. It will evolve much further. But if we abandon net neutrality the internet will look like whatever makes a large ISP the most money.