Well, it definitely isn't a very lucrative giveaway and they might have only planned it for their regular players and it isn't to attract more gamblers towards the platform because if that was the case, they could simply just give away $5 at once to each user a month for any amount of month they want to run the giveaway for, that would make it much better and more attractive.
Although I do not like their free cent promotion but I do not agree with your suggestion as if they give free $5 each month, it will be so easy to be abused because it has no requirement at all.
Imagine if they do as what you suggest, hundreds or maybe thousands of people will create so many accounts in order to get the free $5 then withdraw it as there is no minimum withdrawal amount + no withdrawal fee IIRC.
I think the better option is to have daily faucet with bigger amount like 5-10 cents so players can play few bets after claiming the faucet.
There can always be a way to tackle that and stop the abusers, they can set some limits or requirements like only 1 claim per IP address and no VPNs allowed, that way, the abusers won't be able to keep creating accounts and claiming free money. How many devices do you think a person can have access to only to claim a free bonus every month?
The faucet option is good as well, the point is, that if they are giving away something for free, it should at least be useful and make a gambler be able to try their platform out and place some bets, with this method of claiming a few cents every 90 minutes, it is tiresome and useless in my opinion.