The unavoidable negative bent goes something like, when you're on a call in a shared space you're polluting everyone else's experience. There is a lot of interesting discussion that could be had about headphones too. They solve (?) broadcasting your audio to everyone, but they are mostly one directional, insulating us from our own noise, and it's a weird expectation that others should have them to deal with our noise. I'm overall worried about how normalized it is for us to "take" from this space. Of course, there are situations where it can be quite good for society to provide spaces for this activity.
It's worth repeating the space is shared (and really it's owned by the cafe) so neither I nor any particular patron gets to decide good/evil. But it also doesn't feel quite right to expect or force baristas to have to police.