There are a lot of carbon emissions from a variety of sources. Coal fired power generates more CO2 in the US than all US automobiles combined. Does that mean we should completely ignore automobiles and focus on coal power?
Focusing on the "smallest" problem at the expense of the "biggest" is the wrong approach. But ignoring small problems that are easier to fix is also the wrong approach. The author is using a phone that is more than 6 years old and still functions; making it easier to continue using it feels like an easier problem than changing urban planning.
Coal is a dead man walking, not just in the US, but around the world. Systematic market forces have eliminated any financial advantage to coal. China uses it to fill in for gaps in renewables, but has very low capacity factors for their plants.
IMHO we should spend lobbying efforts on the things that will have greater effects, like approving apartment buildings in walkable areas.
I agree with your assessment that we should change what we can and should optimize how we spend our time creating change, but IMHO the best possible outcome of advocating for phone change is that people think "hey yeah let's change this," but then get told "oh so you are OK with that change, how about something far far bigger for small effort?"
We seriously only need to do very small changes to urban planning to effect massive change compared to phones. And those small changes have the effect of growing. And they are necessary urban planning changes, and the longer we put them off the less likely we can have the snowball rolling where we need it to be.
Focusing on the "smallest" problem at the expense of the "biggest" is the wrong approach. But ignoring small problems that are easier to fix is also the wrong approach. The author is using a phone that is more than 6 years old and still functions; making it easier to continue using it feels like an easier problem than changing urban planning.