The RB211 is quite complicated mechanically in the front bearing area having to support the loads of 3 shafts and allow modular assembly. When you add the further complications of cooling and sealing air and the oil system then it only needs a small movement of a splined coupling axially to be the route cause of all sorts of problems.
I guess that most people on this forum are too young to remember the uncontained fan shaft failures of the '80s - this had particularly amusing connotations (in hindsight and thanks to 4 hydraulic system redundancy) when it happend on the #2 L1011 position where the fan hit the s**t. The route cause of this issue was (too) hot air getting into the front bearing housing through misaligned or worn stag seals and causing a fire there. In time this weakened the LP shaft and the fan vanished up the intake releasing the LP turbine blades in the process and literally cutting the engine in half.
This current problem sounds trivial in comparison.