I've heard it as "commoditize your complements". When you're the heavyweight in a certain market (e.g. discovery and delivery), you want nearby markets to be competitive and prices to be low. You can greatly contribute to bringing that about by getting into it yourself like Amazon has with Amazon basics. They know they'll never make loads of money from those-- it's a highly competitive market after all-- but the better they can make it for consumers, the more consumers will use their actual product, the Amazon website.

https://www.joelonsoftware.com/2002/06/12/strategy-letter-v/