Networks drop packets once they become over-saturated. You can either drop specific packets (e.g. netflix) or you can drop packets indiscriminately (e.g. everyone, including netflix, experiences degraded service). This is a pretty normal, planned-for part of the internet - it's one of the main problems TCP/IP tries to solve (it intentionally slows down traffic if it notices packets are getting dropped) and hasn't been a problem so far in the xx years the internet has been a thing.
Net neutrality covers that, and then also charging for use of some services but not others (imagine Comcast charging for bandwidth to netflix, which it does not own, but not Hulu, which it has a sizable stake in - there are a handful of examples of this having happened before the NN regulation went into place) and blocking certain traffic (see: Verizon blocking facetime) and allowing services of large companies to pay for prioritized traffic.
The end game NN proponents fear is something similar to Cable now, where you have to buy access to websites or protocols ala cart. I don't think that's necessarily going to happen, but I'm 100% sure ISPs will start abusing their monopoly/duopoly to further their vertical integration efforts by favoring content they own or news sources that cover them favorably over indirect competitors or detractors.
Net neutrality covers that, and then also charging for use of some services but not others (imagine Comcast charging for bandwidth to netflix, which it does not own, but not Hulu, which it has a sizable stake in - there are a handful of examples of this having happened before the NN regulation went into place) and blocking certain traffic (see: Verizon blocking facetime) and allowing services of large companies to pay for prioritized traffic.
The end game NN proponents fear is something similar to Cable now, where you have to buy access to websites or protocols ala cart. I don't think that's necessarily going to happen, but I'm 100% sure ISPs will start abusing their monopoly/duopoly to further their vertical integration efforts by favoring content they own or news sources that cover them favorably over indirect competitors or detractors.