These days, merits in last 120 days is the basic eligibility criteria for signature campaigns.
It is campaign paid in bitcoin but with signature campaigns in bounties and paid in altcoins, managers usually don't require merits in last 120 days. Project teams possibly don't mind about post quality too because their tokens were minted from smart contracts, and they don't lose anything for bounty distribution.
I remember CM yahoo once said like "slots in campaign is not a right but a privilege". If you agree on this, then I guess long term holders deserve slots in campaigns.
A holder is a holder and a poster is a poster. Not all Bitcoin holders want to join signature campaigns, and very few Bitcoin holders are Bitcointalk forum members. If a person is a Bitcoin holder, it does not cause to that person is a member here, and more important is a good poster.
If you are a company, hire a Bitcoin holder into your signature campaign, pay him, but he is a shit poster, are you ready to spend your bitcoin this way?