I think everyone in the community has a firm barrier between "things are fun" and "things are real." Many of our working sci fi writers these days are big science nerds who have a firm grasp of reality but explore the impossible corners because they're entertaining to think about. I think if you asked 100 trekkies whether Star Trek represents "a realistic future in space" about 95 of them would aver. They know in their hearts that warp drives and replicators have no more basis in fact than magic wands and ruby slippers but they can go what if and enjoy themselves and that's totally fine.

The problem is our paradigm for "meeting strangers" is generally "after crossing an ocean" so the ocean has to be challenging but not impossible to cross. You're right - from a realistic standpoint there's orders of magnitude more logistics in crossing light years than there is in crossing leagues but this graph or its friends will tell any creative writer that where there's a will there's a way, wave hands get plausible deniability and move on to the fun stuff.

MY beef is that articles like this one are generally written by people without the creativity to write the fiction and without the smarts to write the fact so we end up with wrinkled-forehead prognostications about the Kardashev scale. The Fermi Paradox white papers are often scientists messing about with science fiction but this is... something else. It kinda looks like the author heard about the noosphere while ripping on a bong in his undergrad and never let go.