I think it's definitely a step in the right direction for onboarding new people rather than HP, unless you absolutely know that you can trust them. It should be stated up front that it's a delegation that has an expiry date of your choosing or the scenario that nonameslefttouse will come in for sure. Either way, I think it's still a safer bet in terms of protecting a reputation having delegated RC rather than HP as it doesn't have the waiting period of 5 days to undelegate.
Will be interesting to see how it will play out. I don't know how anyone will be able to abuse this, there's not a huge amount they can do with RC really.
Glad you were able to use it on Splinterlands :)
With RC delegation, it wouldn't even need to be announced, as it can be dynamically applied. The accounts that get them wouldn't get too much, so they would still be limited, but get a taste of how things work without upfront investment.