Because we don't know if Hive account@pumpkin / Hive account@freedom is owned by Steemit, there was considerable pressure for witnesses to go along with Steemit Inc and this hardfork.

This has been the case for many HF now. The majority of the top witness would drop out of top 20 if they were to lose Hive account@pumpkin's vote. Hive account@pumpkin's influence goes beyond the top 20 witnesses.

Hive account@blocktrades also has a substantial influence on the witness ranking. He only votes for 5 witnesses at the moment. Hive account@blocktrades' proximity to Steemit Inc also creates pressure for top witnesses to get in line with Steemit Inc.

These pressures, although not ultimate factors, have created with this HF and in the past, situations where there are high risks to go against Steemit Inc's HF (and potentially lose Hive account@pumpkin or Hive account@blocktrades' vote) with very low possibility of reward, (delaying, stopping an hardfork while proving it was justified).

This is one aspect of Steem which would benefit from more public exposure.