I've had similar seat blocking elsewhere but the seat allocation computer does it.
BMI UK domestic flight, about 50 pax on board, Y class only, one of the old BMed A320s (about 120 seats) with substantial club class cabin had been substituted. No pax allowed to sit in the business class seats up front (don't know why not), and to balance things out nobody allowed in the rear 6 rows. Everyone thus squashed 6-abreast abeam the centre of graity.
As most had paid very substantial full fares on this early Monday morning flight, not impressed. Done entirely for operational convenience.
Originally Posted by Slim Shady
As Ryanair operates within Europe, primarily, 15kgs baggage allowance is 2kgs more than the prescribed figure for weight and balance.
You are confusing average weight (the European allowance) and maximum allowed weight (Ryanair's figure). Quite different items. The European allowance average envisages a proportion of pax with no checked baggage at all. The average figure should be obtained by periodic sampling.