Shimano's actions here make perfect business sense and have been predictable.

Shimano sells low-margin groupsets to bike manufacturers in order to create market share among the bike buying public. It highly encourages (!) the bike brands to adhere to this all-Shimano solution. As an aside, it also uses patent lawsuits and proprietary standards to assist with this strategy. So the overall objective here is to as lock up the OEM market.

Aftermarket bike components are priced much higher simply because they can be. Once a rider is locked into the Shimano system, and they break a derailleur, then they are motivated to pay a lot more, as the alternative is a new bike.

The problem for Shimano is that mail-order houses have been buying up large lots of OEM parts, targeted for whole bike builds, and then selling them at a discount to Shimano's aftermarket parts pricing.

Bottom line is that the mail-order houses have have been putting a stick in the spokes of Shimano's corporate strategy.

So Shimano needs to shut this end-run down.

​​​​​​​The ultimate goal is monopoly control of the supply chain, including the OEM market. If this is possible, then the price of new bike groupsets could jump substantially, as there would be no practical alternative.