Because they doing it obvious on the forum which everyone can see.
How about they doing this on facebook messeger, telegram, twitter, email with personal message?
Who will catch them, tell me?
Not so hard to catch. In fact see your own merit summary:
https://bitcointalk.org/index.php?action=merit;u=1186307It looks suspicious.

What is it look like?
He gave me merit and I read his profile, I read his post. I agree with what he saying on that. Did you read his post which I gave him merit? I guess you didn't. He got the same point with me. Please make more research before letting all people know you are an angry kid.
Here is the page I gave him merit,
https://bitcointalk.org/index.php?topic=2779298.msg28935057#msg28935057I am not doing the dark thing, I don't scare haha.
Should I ask you for a permission to giving my favorite people merit because we are in the same page?
Are you jealous with that?
What a kid!!!
And one more thing, a lot of members pm to support my point. They just don't want to argue with these people, included you. Wasting their time.
I am doing the thing by getting the right for them.