For member or full member accounts, I can understand since it's easy to get merit to rank up to that level. But for Hero/Legendary, yeah I don't get why they throw away such accounts and reputations for weekly payment from a scam campaign like 1xbit. I suspect most of those accounts are alts or multi account or already have a low reputation already.
That means they can anytime ditch that account for another or give merit to rank up a new account.
When the merit system got implemented those who already had rank earned by activity received "airdropped merit", Hero Members received 500 merits and Legendaries Received 1000 free merits. This means that today in order to have a Legendary account to throw away by joining 1xbit, that account just needed to have activity and be old enough to have received free merits in 2018.
What actually you are saying is that those legend accounts that joined 1xbit didn't work so hard to build their account from zero to legendary, since they received airdrop merits. You are right if it is what you meant. I have another approach to this. If the purpose of someone is to make money in the forum only, those legendary accounts didn't just spoil their accounts but they have made good money for over 1year. 1xbit started with $150 per week and they have been consistent in running multiple campaigns.