Discussions without politics are a bit like science without the mathematics field: If you take the larger definition, there's hardly any way to avoid it. Especially if you define things like crypto currency as political, it's basically impossible to have a tech discussion without scratching it.
What people mean when they say that is that political topics are usually a side concern to the technical topics at hand, not pure political discussions. The off-topic, angry and/or ad-hominem comments are also quite rare - yes, they exist, but compared to (most of) Reddit and Twitter it's very relaxed. And policy is almost never the primary topic, unless it directly affects the tech field.
What people mean when they say that is that political topics are usually a side concern to the technical topics at hand, not pure political discussions. The off-topic, angry and/or ad-hominem comments are also quite rare - yes, they exist, but compared to (most of) Reddit and Twitter it's very relaxed. And policy is almost never the primary topic, unless it directly affects the tech field.