I think their main purposes of using social medias is to rank up only in search engine like google and bing.
In my experience in marketing if you wan to rank up your website like in google you need more signals from twitter, FB, instagram and any social media the more people mention your website or project you are gaining authority that might boost your rankings in google or any search engine.
If it happens the project or the website might rankup and it may pass the other crypto related competitors in google rankings that related in crypto.
Honestly, SEO marketing out there in social media will boost your site traffic. Much better to try it make your own website and find someone to promote your website through social media accounts but make sure that they have different IP's because it may ignore those accounts from adding it as a real user so if they have different IP they are fine.
So for me it's not really useless you will see the result after few months this is SEO strategy that until now working as of now based on my experienced I am not promoting any ICO project but I'm promoting some product and affiliate links before.