There's tons of back and forth on this, but what I've heard is the reason these rules were set up by the FCC was that the new classification status of ISPs as c

There's tons of back and forth on this, but what I've heard is the reason these rules were set up by the FCC was that the new classification status of ISPs as common carriers took them out from under FTC regulatory authority. I don't know the motives for the votes on this and afaik most members haven't commented to explain themselves. There are some particularly libertarian-leaning Congresspeople, like Rand Paul, who would clearly support it out of principle. We assume that others also support it out of ideological sympathy, and that everyone else is trying to play nice with the party leaders by going along with it. You are 100% correct that a great deal of these legal modifications are technicalities that are touted as disasters for political convenience. Let's not forget that the Republicans did the same thing when they pretended that the sky was falling over net neutrality going into effect, claiming that Obama was trying to "take over" the internet. Whether one agrees or disagrees with net neutrality as a policy matter, those claims are absurd. Political parties, and especially the parties not presently in power, are always going to be trudging this type of muck up. It's very tiring, from both sides.