Abroad a meal can run two to three hours (mostly spent NOT eating or nibbling, just maybe drinking a cup of coffee or an adult beverage).
Here the waitstaff are apportioned sections in a restaurant. If you aren't buying anything, and you don't know to tip accordingly for tying up a "station", you are denying them a sizeable portion of their daily paycheck. It is considered inconsiderate. If there is no table service and there are not people waiting for tables, it is not an issue.
The older I get, the less I like waitstaff trying to clean the table while I’m still at the table. I consider that rude. I don’t like having food or silverware dropped on me or someone reaching across the table to grab a dish while I’m talking to a guest. I’ve seen this grow worse over the past 30 years or so.