Comparing social media campaign and signature campaigns depends on a few things. If you are targeting people who are crypto-enthusiasts, then signature campaigns will prove to be more effective than the social media campaigns. If you are targeting people of all walks of life probably to educate and gain new signings, then social media campaign will be more effective than signature campaigns.
I couldn't agree more with you, it's based on the target market and so each has its strength and it depends on the campaign manager's ability to maximum his campaign by adopting the right platform. At times it's good to advertise among people in the crypto world and sometimes you target outsiders depending on how you want to reach out.