I'm afraid that every referral programme will result in spamming.
I take your point it may result in influx of users and it's quite safe for them as they would be able to change post beneficiaries or this feature will dissappear in time or after numbers of actions.
But you have to bear in mind that all* of big and legitimate platforms allowing referral programmes are using only verified users - whales, not plankton. But the implementation of a privileged group would be hard and morally debatable in a decentralised community.
*OK not all platforms, but the big ones I know, like Alibaba.
I guess, they're doing so especially to exclude excessive spam, that IMHO can hurt the platform. Google doesn't like spammy sites.
The idea for dApps that have creation service to may allow users to automatically set the dApp as a beneficiary, may be as close to the referral programmes of big players, as possible.