There are many ways to combat churn. My point was that doing what is right to make the customer happy can be an awesomely powerful and more importantly POSITIVE weapon in the battle against churn.
Platform lock-in is a negative, customer-hostile approach. The positive alternate version of "lock-in" is "stickiness." Ie. the concept that your product/service/experience is so amazingly awesome that your customers have many reasons to keep coming back and using you.
Platform lock-in has always come across to me as a crutch for some flaw in a product/service/pricing model. I understand businesses need to manage risk and their investment in customer acquisition, but focusing on customer-positive ways to do so seems better aligned with all parties interests, no?