IBM continues to add value to the client, such as Network DDE, Network clipboard, and peer support. Customers only need to upgrade the client to gain new functionality or stay within support requirements. Even then, the upgrade is on the customers' time schedule, not IBM's. This means that any number of versions of LAN Server can interoperate together, sharing data transparently to the end user. Individual servers can be upgraded, leaving other servers untouched.
Migrations are tough on personnel, and really difficult in the world of client-server computing.
No longer is an update to software a single update to one software package on a central CPU with dumb terminals. A change to a single line of code could mean that hundreds of servers and thousands of clients need to be updated. These upgrades can be done on their time schedules, not IBM's. User disk limits are needed on servers holding data. Meanwhile, the application servers and existing clients can continue to run unchanged with a previous release of LAN Server.