Too funny ... once again I was searching for something entirely different and happened to get this thread in my results!
I voted for “necessary” although that isn’t quite the word I would use. I think punk gave music, particularly rock of course, a good kick in the butt, and not just musically but influenced bands and musicians in other ways too.
Going off on a slight tangent ... I remember feeling at the time that punk, while it seemed new and exciting also struck me that a lot of band members and their fans appeared very narrow minded. Only punk, any other kind of music (looking for a polite term) was terrible and you were really lame if you liked prog, arena rock, basically anything from the 60’s and 70’s that is now what is referred to as “classic rock”, pop music and heaven forbid disco. Me, being the way I am and was then as well, I definitely used to have some weekends and even consecutive days of the week where I must have seemed like a multiple personality – punk one day, disco the next day and rocking out the next. Fortunately I knew some of the sorts of punk people who did see the bigger picture musically and most of my other friends were fairly well rounded types musically. (Once upon a time I was the one seeking out new and different and sometimes off-the-wall music and now I'm the old fuddy-duddy I promised I wouldn't become!
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In hindsight, one thing I give punk a lot of credit for is what I think I’ve referred to on this forum as the “punk DIY ethic”. A number of punk bands went ahead and put out their own records, did their own marketing, etc., directly to and for their fans. Bands such as early Def Leppard and Diamond Head took note and started out by making their own records and doing their own merchandising though of course their music was somewhat different. Also the punk ethic encouraged musicians who might not have been absolute virtuosos in the beginning to go ahead, form a band, get out and play, etc. The way I see it I have punk or rather their methods to thank indirectly for some of the other rock bands who came along during and after punk who I enjoyed then and some of which I still enjoy now.
P.S. IMO “new wave” was a label given to I think any music slightly off-the-wall at the time, perceptible as fit for consumption by the general public ... more or less. Funny how in hindsight most “new wave” of the time can be categorized into other genres ... including ... they were punk, people, deal with it!!!