The US used to heavily punish that sort of behaviour, but in this case it took EU action to reign in a US company
FWIW in this case it was Chinese action - China is requiring all phones sold domestically to support RCS. The EU DMA would have forced Apple to open up access to iMessage, not implement RCS, but they found that in the EU, iMessage market share is too small for the DMA to kick in (probably due to the overwhelming popularity of WhatsApp).