I was a PM in a long ago prior life and, at one point, we decided to bring development managers into more customer meetings. It wasn't a bad idea but they had their "day jobs" so would end up being only in a few meetings. So it ended up as almost mirroring sales where the last customer they spoke with was taken as gospel and a blueprint for what we ought to be doing.
To one of the broader points, in both my personal experience and what I see software PMs doing in my current non-PM role, they spend a lot of time talking to customers.
I worked in a role in healthcare for a few years where I was the lead engineer and sat in on most customer meetings, and even did some field observations. It was an invaluable experience. It was super useful for disabusing me of certain notions I had about which features mattered. I learned a lot about product work from the experience and started asking myself and the team different questions during the development process.
I got to see a broad swath of users with pretty different needs, and learned a lot about how their clinics worked. It was really good for thinking concretely about tradeoffs.
To one of the broader points, in both my personal experience and what I see software PMs doing in my current non-PM role, they spend a lot of time talking to customers.