In my 30 years in the organization, I had never heard of this. It was quite common for all of us to associate with, and ever work in field service with ones in neighboring congregations. The Elders that I knew spent quite a lot of time with friends in other congregations with no complaints from anyone.
I’m wondering if this was just the rigid opinions of some local yokel Elders. One aspect of “Local Needs” talks I noticed was that it could be largely shaped by the personal feelings, intuitions, and bias of a local body of Elders. They could have certain pet peeves about where friends choose to sit in the hall, people getting up to go to the bathroom during the meeting, certain fashions, or people spending too much time on recreation. The talks are often deliberately vague as to try not to “call out” any specific individuals, while prompting people to take the messages personally.
And to be quite honest, many of us did not take these talks very seriously. Many of them seemed very childish and pedestrian, much like someone reminding an adult to chew their food properly, or to lock their car doors.