After 13 years on 737s various, NO FCOM which I ever read, explained the taxy crabbing.
1 day, when I was awake, doing the walkaround, I noticed the dampers on the torque links and limited castoring ability of the MLGs and realised this was how the 'frame could accept a touchdown in autoland 15kts X-wind without "squeezing"the drift off.
NONE of the TRIs/TREs of any of the UK regulated companies for whom I worked could answer the question and when l pointed it out to them subsequently, they looked suitably sheepish and surprised a G O F like me had reasoned it out.
Not one single Boeing/Company publication mentioned this mechanism on the 737 MLGs.
Hence the ability to taxy whilst pointing in a different direction!
Try pushing a supermarket trolley at speed and you'll soon realise the need for dampers on the NLG?