I believe it is an implicit "you make them look shoddy" if your product doesn't work after they change something. Self-produced ones at least they can check for

I believe it is an implicit "you make them look shoddy" if your product doesn't work after they change something. Self-produced ones at least they can check for backward compatibility but they have no way of guaranteeing any of their changes would break any fly-by-night or obscure adaptors. Rather overkill in practice for a legal doctrine. But I can see their concern, and why a company would dislike it over the sheer tech support call volume alone. Their first response being "stop it!" makes sense in that light. Open standards are a good way to prevent issues while keeping both sides happy (notably it also keeps company names out of it except in deniablenways such as say listing GMail as an example of a POP3 user - it doesn't equate the two). Open standards aren't automatic or free though and there may easily be gaps because they never thought to specify a given portion for interoperability.