I don't see being a witness that way. There may be some politics in the campaigning of a witness - but there's no governance for the most part in Steem. We don't have super secret meetings where we decide what happens next. We talk a lot about what we'd like to see next - but we aren't making those decisions.
Instead what we are is essentially gatekeepers of the blockchain. We are paid to produce blocks and occasionally decide what changes are allowed to happen on the blockchain. We can campaign and promote ourselves as more than that, and you can vote for us for those reasons, but it's not required or part of actually being a witness.
The key point to all of this is the blockchain and understanding that the blockchain is not steemit.com. When it comes to steemit.com (the website), communities, the development of SMTs, the priorities of tasks in development, or almost anything else - witnesses have very little say in the matter. Pretty much every change you've seen since June 2017 has been outside of the purview of witnesses.
To Steemit Inc, witnesses are block producers and they are paid to produce blocks and consider changes in blockchain consensus. Those witnesses may also be "other things" on top of that, but the official witness responsibilities of each of those people/groups ends there.
I would hope that my track record so far as a block producer would at least give me the benefit of the doubt when it comes to being a "conflict of interest". If it becomes a problem and people see me making decisions that favor one chain over another - then I'd expect to be voted out.