Backward compatibility as a marketing feature
Most companies treat backward compatibility as engineering hygiene. The companies that lean into it find it's one of the most under-marketed product features they have.
Maintaining backward compatibility is expensive. Engineering teams resent it. Product teams forget to factor it into roadmaps. And yet, customers — particularly enterprise customers — buy from vendors who maintain it over vendors who don't.
Why customers care
Every breaking change a vendor ships is an engineering project on the customer's side. Customers add up the cost of those projects when deciding which vendors to keep. A vendor with a reputation for backward compatibility saves the customer money — and the customer notices.
Marketing it
Most companies don't talk about their backward-compat policy because they don't think it's marketable. It's actually one of the most credible differentiators in enterprise software. "Our APIs haven't broken backward compatibility in three years" is a sentence that closes deals.
Backward compatibility is enterprise marketing dressed as engineering hygiene.