I thought the phrase was "dear sibling" since "big" might not be sufficiently inclusive.

True, it would discriminate against smaller companies.

dear would discriminate against those who are not so beloved.

To be clear, its the best comment because "...it has always been big sibling"

These approaches have a way of wiping the past clean off the slate. There's no problem with the words 'big sibling' - I, as a big sister, am in favor of it. The problem is that the internet is a snapshot pretending to be all of history.