[PurpleRamen]

Because they break the existing behavior. And Debian is all about stability and reliability, unlike OpenBSD, which aims for uncompromised security. Nobody would have complained it Debian had done this from the beginning, but when they break it, people complain.

[transportheap]

openbsd was just an example. other distros and os do patches all the time including changing features but only debian gets called out.

[PurpleRamen]

Those patches are usually backports, for security, or better integration. They do not break something on purpose.