We took a Scandinavian cruise on Celebrity Apex and didn't have to talk to any other passengers during meals. The main restaurants on Celebrity Apex is like normal restaurant where they would sit you by your party and just your party. You will be very close to the other tables and can clearly hear conversation of other parties. But no one would cross conversation just like in a regular smaller restaurant.

Our first cruise was like OP's experience. It was on Disney cruise and they sit our family of 3 with another family of 3. I can see why they do that as our age are similar and our kid's age are similar. But we just couldn't be any different and it was starting to be awkward after a few times. Then both family decided to skip main dinning and go to the buffet instead. But then we saw each others at the buffet and that's also awkward but at least we get our own table LOL.