It's a two way street as far as responsibilities go, however the solution that was most often relayed to Steemians was to go check the three relevant tags.

#witness
#witness-category
#witness-update

Which really isn't a solution, taking into consideration that anyone can use them, which is fine as a general topic, but isn't a solution and answer that helps a Steemian to get what s/he wants.

Can a new member of this blockchain know off the top of their head who is or isn't a witness among all the posts with those tags?

and asking a Steemian to go physically scroll through three different tags and to filter out posts by Witnesses out of the masses, well, tbh. it was something that used to upset me when I wasn't a witness. So one of the line items on my "to do list" was to find a solution to this and make it simple, so that EVERYONE can have ALL the relevant information in front of them with one click.

Hopefully one day Steemit Inc and other whales see the potential @witnesspage is offering to promote and stimulate not only a reliable source of information flow, but also for a way to encourage people to complete all their duties and responsibilities from all sectors of our ecosystem.

All in all, I wish it was around back mid last year, would have my life a lot easier!

Cheers!