He does provide a service, albeit a very small one. He puts all of the tabs in one post filtered on a category. So I could see how his posts may save some time for a few Steemians.
Does downvoting decrease your voting power? If so, steemians might be better served to have you direct rewards to more valuable posts.
This is also on the post:
If you think your posts are good quality but undervalued, please do following:
a) send links directly to us as we will try to curate
(upvote & resteem) as much as we can
b) use our special tags: markboss / markboss-promo for your posts - we will upvote / resteem for free
c) use one of following popular "booster" services to upvote your posts and earn more money:
I don't know if he has taken such actions, but he at least claims to have that as an intent.
Please don't downvote; instead, give us suggestions how we can make this great service even greater.
He seems to be calling out to you specifically. Have you tried to engage him directly, other than downvoting?
I'm not trying to be critical of your actions, just trying to rationalize all of it