I am not arguing that people have no agency. I am saying that agency exists within real world constraints and those constraints matter.
Yes, in an ideal scenario, people would have the time, space, energy, transport and emotional capacity to deal with possessions immediately and routinely. But for many households, especially those dealing with illness, disability, caring responsibilities, financial pressure or bereavement, life does not work in tidy systems. Things accumulate not through neglect, but through necessity, uncertainty and limited capacity.
Regular disposal also assumes that disposal options are consistently accessible and appropriate. They are not. Charity shops refuse many items. Recycling points are limited. Some things have no clear ethical destination at all. That makes responsible action harder, not easier. You can see how varied it is with people's posts.
You are also treating predictability as the same thing as control. Yes, families can predict that children will grow and need new things. What they cannot always predict is timing, finances, storage space, health or whether items will be needed again for siblings or changed circumstances. Keeping things is often a practical choice not an environmental failure.
On sustainability, I agree the average British lifestyle is not environmentally sustainable. But environmental responsibility is not an all or nothing position. People can make meaningful efforts within imperfect systems. Reducing waste, reusing items, and avoiding landfill where possible are valid actions, even if they exist within a wider unsustainable structure.
It is also unrealistic to suggest that people must fundamentally redesign their entire way of living before their environmental concern becomes legitimate. Most people are doing the best they can within the limits of modern life.
Responsible behaviour does not only look like perfect systems and minimal possessions. It also looks like trying to make thoughtful choices with what you already have, even when the process is slow, inconvenient and emotionally difficult.
That is not avoidance. It is real life.