Almost every problem can be divided into many tiny ones, and solution to each tiny problem can be ridiculed that it solves only tiny bit of a problem.
There are bigger problems for sure but there is also "there are bigger problems" fallacy (aka fallacy of relative privation).
I'd rather have people kick back on their couch and watch a Netflix DVD instead of feeling great that they saved so much plastic, and then smugly drive their SUV to the next shopping mall.
It's probably an impossible question to answer.
As an hn'er you should be used to premature optimization ;)
In reality of course there are a few big things that matter, and lots of tiny things (like Netflix DVD rentals) that don't. Two of the main sources of plastic waste are the packaging and textile industries. If you have a fast fashion habit it's pretty easy (and, at often single-digit $ prices per item, widely affordable) to rack up a few kg of plastic waste per year (a non-trivial fraction as micro-plastics). Now how much plastic waste do you estimate a Netflix DVD habit creates in comparison?
The best case scenario of the innumerate and self-righteous setting environmental agendas is that rather than addressing the big problems, attention gets frittered away on non-problems.
Often, of course what happens is that you end up with something that's much worse than doing nothing. Like for example the bogus plastic recycling policies enthusiastically enacted in much of the Western world, which saw to it that a lot of stuff which would have ended up harmlessly in landfills was loving hand-cleaned and shipped around half the world to Asia to be then dumped into the Oceans. Or “Green” politicians building brown coal plants like crazy.
You are comparing single DVD rental company with whole textile industry -> fallacy of relative privation.
Some of us just see a positive that less trash will be produced, less stuff will be moved around and you start mentioning "setting environmental agendas". How are those thing related? We cannot be happy until in single stroke we fix over 50% of a global problem? That will never happen.
You mention plastic recycling - I agree it is either pointless or harmful, depending how you look at. it. Do you really consider that not producing trash is also a failed policy? If not why are you doing this comparison?