Twitter - the new graffiti

From my mate Andy: With the ability to freely express ourselves, almost instantaneously, through social media, does this new facility undermine one of the oldest forms of offline social media – graffiti?
Also, is social media the ultimate form of defining your urbanity – in all senses of the word? Can we measure this repercussion of the impact of social media – is there less graffiti around?
In my creativity and innovation teachings I do see graffiti and Twitter as both forms of creative expression. If you think about why do people write graffiti? I suspect it is motivated by:A need to express a response, an idea to a situation

• An outlet for rage, boredom or despondency
• Adding to or responding to other graffiti
• Marking out some territorial space for you or your allegiance
• Demonstrating your allegiance as well as your wit, humour or insight – your urbanity
• An expression, for some, of their artistic ability

I was inspired by the topic after coming across a piece of graffiti from ancient Pompeii, which read: Wall! I wonder that you haven’t fallen down in ruin, when you have to support all the boredom of your inscribers.
My experience of graffiti falls far short of the elegance, the urbanity, of the Pompeii piece. Perhaps, it was in higher education, the loos at the library in Swansea University – I had to make some use of the building’s facilities! – whose graffiti I most recall.
A Welsh nationalists call to hit the English with: Don’t flush the toilet -  England needs the water and an answer from someone presumably from Albion with the rejoinder: Don’t flush the toilet – Wales needs the sh*t raised a smile. (In hindsight it is not particularly funny, but demonstrates the power of context and immediacy in giving cultural value to something – which doesn’t bode well for the longetivity of much social media content.)
And perhaps my all-time favourite of a plea from another student in 1980 facing the prospect of leaving the safe world of university life: But I don’t want to be an Asst. Area manager for Sainsbury’s to which another wag added: But what else is a BscEcon good for! - which you need to have been at Swansea for, to appreciate the significance.
Of course, no review of my life – and the graffiti it has witnessed – would not be complete without acknowledging the universal words scratched on the metal casing of all Durex machines in men’s bogs across the land: This chewing gum tastes awful. And next to the kite mark with its guarantee of quality, the words: So, was the Titanic!
The question remains, is there less graffiti about – whether it is the toilet cubicles of university libraries, or in everyday life?
My anecdotal evidence is yes. And we have not just witnessed a decline in volume but also, graffiti is reflecting underlying dynamics in changing trends.
It is now in two camps: premium, whether in its ultimate form is a work of art by Banksy or your neighbourhood street artist, or has become more basic and commoditised, with either just cheap or common statements of just a football team name.
The word ‘urbanity’ does not just mean being charming or considerate, but also of being of an urban area. Is graffiti and now social media an ultimate expression of ‘urbanity’- of living a life in an urban context?
What’s your view? Is there less graffiti about? And what has been the impact of social media?