Let's flip this around and see if it still fits:

"the PM can't be expected to sit in meetings all day, they need to learn the coding side of it too so they know the potential limitations of the features they want to suggest"

But if a PM does have a technical question, they don't need to go google stuff and figure it out - they ask a developer.

Likewise, when a developer has a product question, why can't they rely on a PM to answer that for them? Why must we also be expected to be in customer meetings and putting in extra effort, when PMs definitely won't put in effort to learn the technical side?