I guess it will have to be an agree to to disagree. You are correct that NCL has more two tops than most other cruise lines but I've cruised NCL a lot (Top Tier) and I have found that you can get a table quite often if you want to share. It is more likely to happen at peak times.
You are correct that people will ask for a table size for their party and their party only.
However, the problem of waiting for a table is pretty rare. Like you, I have had little wait for a table and when I have it wasn't long. NCL has been doing open seating the longest of the major cruise lines and they have their system down to a science. On Celebrity and Carnival they still have a number of glitches and sharing a table is encouraged on those lines.
Take care and no one should worry about a long wait for a table.