I've only ever seen it to mean "individual contributor", but then this would make it odd/bad advice. There should only be 1 "customer". Sure, that customer may have a whole team that actually needs the product, and may provide them for clarification or what not, but to avoid unrecorded/incorrect handshake agreements, specs, or pet requirements that have nothing to do with the initial product ordered there should only be 1 POC for the product unless otherwise specified.
When multiple teams are using the thing, talking to at least one developer on each of those teams is going to surface things you won't find out anywhere else.
I agree that an individual user shouldn't be driving roadmap stuff directly, but getting their perspective, pet peeves, war stories etc. is still valuable advisory input to the overall process.
You should keep a record of what you're doing and why, but getting clear and accurate feedback from the real decision makers who have control over the technical success of your product is essential.
Despite all that, I still find it absolutely necessary to get in the same headspace with someone on the other "side". We can and should always float any outcomes to the primary points of contact on either side, but a POC is a primary point of contact, not the only point of contact.
Put differently, interfacing directly with customer ICs is good and necessary, so long as it's done with the go-ahead and oversight of each POC.
I've only ever seen it to mean "individual contributor", but then this would make it odd/bad advice. There should only be 1 "customer". Sure, that customer may have a whole team that actually needs the product, and may provide them for clarification or what not, but to avoid unrecorded/incorrect handshake agreements, specs, or pet requirements that have nothing to do with the initial product ordered there should only be 1 POC for the product unless otherwise specified.