There is no denying that it had far-reaching affect on the music scene but it was a relatively small genre of music followed by a relatively small number of people over a very brief period of time. 

Those most affected by it were the music journalists whose written "history" of this time many people today get their perceptions from. The music-makers followed on from that, they were not going to create and promote music that these journalists would not write about, but these music-makers (and by that, the music industry) did not start producing Punk Rock as a result of that.

By a process that evolutionary biologists call punctuated equilibrium the advent of the Punk ethos within the music scene created a step-change that found a new stable equilibrium state that bore no relation to the trigger that Punk instigated. This stable state was what we called at the time New Wave and encompassed a wide gamut of music subgenres that were more readily adopted by a larger proportion of youth than Punk had managed to reach, many of these emergent subgenres were themselves the antithesis of Punk. Even bands that had been closely associated with the Punk movement of 1976 were quick to create post-punk new-wave music that had no direct relationship with Punk Rock. It is this post-punk new-wave ethos that many pre-punk musicians adopted, if not wholly musically, at least in style, image and attitude - if only as a result of getting their hair cut short, wearing narrow trousers and thin ties. While it was amusing to see Peter Gabriel perform a Punk version of White Shade Of Pale on stage, the stripped-back music he recorded on his albums owed more to applying New Wave attitudes to his Progressive music background than any slim-pickings he could glean from Punk Rock. 

I'm not sure if "real punk" ever fully existed, the DIY Punk ethos by its very anti-consumerism was destined to appeal to a very limited audience. Even later hardcore punk bands like Crass (formed in 1977, so I reserve the right to call them "later") were at the Performance-Art end of the DIY Punk spectrum.

Yup, Punk was imported into the UK from New York. No one can deny that fact, and in fact, no one is claiming that Punk was invented in the UK, if it had been we would have probably called it Yob Rock. 

The back-to-basics reaction to Prog in the UK prior to that was Pub Rock, as typified by Bees Make Honey, Dr Feelgood, The Stranglers, The 101ers, Ducks Deluxe et al. This was itself influenced by garage rock from the USA and British R&B of the 1960s. Wilko Johnson's staccato guitar playing was in turn influential on Tom Verlaine's guitar style... nothing is created in a vacuum.

The Punk scene in the UK and the music it spurned was radically different to that of the USA, just as British Psych developed in ways that USA Psych failed to do. Parisian Punk... whatever did that achieve?