Why do people only ever talk about the carbon footprint

To be fair that is not what occurred. The comment was significantly more rounded than that.

Microplastics are the big focus right now, so actually bringing up carbon footprint diversifies the discussion. You’re actually saying stop - don’t bring that up?

I’m old enough to remember when plastic bags were considered the friendly option because they cut down trees to make paper. Anytime people focus only on one aspect, we come to the wrong decision.