Using the network, changes to a programme can be made just once by computer programmers among the users, often free of charge, and then tested immediately on thousands of interested users with many different applications, usually at no cost.
On the other hand, if a company make changes to a programme, it must not only fix the programme, but also check that the new version works properly in tandem with other programmes that have been written by its partner companies. Further, the changed programmes are tested formally on a relatively small group of users, so that the likelihood of identifying all new undesirable programme features is lower.