Easy one - airlines are trying hard to operate on the schedule. In case of irregularity it is always the pax on the first affected sector who will suffer the most. It may look unfair but it is the best option from operational perspective to deal with rerouting100-150 pax on the first sector and carry the rest more or less in time than to have a domino effect. A320 family aircraft within a major airline environment is operating an average of 6 sectors a day, so 150 pax irregularity is always much better than 900 pax irregularity. Ref EC261 it is again only the original outbound sector pax who will not get anything in compensation due to force majeur factor but all other sectors will be eligible for compensation - proven many times in different courts.