Checking BPs at the a/c has been SOP in NZ forever. Many instances op pax distractedly trying to board wrong a/c. Even cc checks can be wrong occasionally.
A 'famous' case:
LAX, never the most user-friendly for SLF. Boarding call made for pax to Auckland to board at gate XX. Couple settle in for the flight. After a while, male of couple opines to female that flight seems to be taking longer than expected. CC called and asked when flight expected to arrive at Akland (Ohio). Auckland/Akland can sound the same when heard in a terminal from a tannoy.
This only shows that even a check at the a/c can miss an error. Just another instance of all the holes in the Swiss cheese lining up.
Take any one check out of the process and there are fewer holes required to line up before errors occur. I believe Air NZ flights on this service have since been boarded using the announcement "... to Auckland, NEW ZEALAND, ...". At least the hole in that slice of cheese is made smaller.
As mentioned by earlier posters, as a matter of course I carry my BP in my hand until seated on the a/c, where upon it is placed in the seat pocket in such a way that it is still visible and easily retrieved. No hassle, really.
Le Vieux