I had this very thought today, and in fact it was around blood donation. Many of us mean to do good deeds, but don’t get round to it or put it off, and a nudge or signal can make that difference in normalising, mainstreaming, motivating, etc.
This is precisely what I dislike about SM virtue signalling. There is so much of this on the stupid school or kids extracurricular activity WhatsApp groups.
You lot all want to nudge us and influence our behaviour, make use do thing you see as worthwhile in that millisecond before you move onto something else. You also believe that we, who don't promote our views in this way have never considered this oh so worthy thing, for all intents and purposes, we might have been supporting refuges, cleaning up rubbish along the river banks and supporting homeless charities quietly and modestly for decades.
Everyone is communicating on SM to promote their views and actions with the purpose of making others change their view and behaviour and to be seen as on the right side of history.
This is what fucks me off most about SM, it's so self important and blinkered but at the same time it comes across as quite unsophisticated (sorry). Social interactions are limited to the promotion of your best assets, attributes and pet ideologies. It's incredibly unsatisfying and so dull to engage with people on this basis.
The needle icon, I mean how plain can you get? I am hugely for vaccines, have had 2 plus booster, teens had 2 vaccines each, I devoured Sarah Gilbert's book but would I stick a friggin badge on my profile to 'oh so subtly' influence others to my superior world view? Hell no, I'd rather have a reasoned in person discussion and don't need a stupid girl guide badge to validate me. 
I actually feel a bit sorry for those who feel that this is the only but of influencing power they have.