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In response to the original OP: The world certainly needed Punk in the Late 70's, and this includes everyone who started a lot of what was to be called Alternative later on.

Thanks to Punk, there was an interest in DIY. True, some of the best known bands were on majors, but by the Late 70's, there was Rough Trade which sparked all of the others. Indie can thank Punk for that!

Thanks to Punk, there was an interest in alternative Political ideas.

Thanks to Punk, Synths were in demand enough for companies to make them more affordable when musicians wanting to play like Kraftwerk wanted to do their thing inspired by the Punk movement, but in a different way. This led to Synth Pop, but it also led to EBM and (more importantly) the more influential Electronic side of Industrial/Post Punk (Cabaret Voltaire, TG and plenty of others). Indie-wise, it also led to Mute Records. On the US side, early Devo was also a part of the early days of Punk as well.

And that's for starters, and these are all connected to Alternative in many ways. There was also the Punk/Metal Crossover that helped Metal gain back it's edge after being almost swamped with Hair Bands.

Plus, there's several legendary bands from Post Punk and Alternative that started out Punk that turned into a different kind of animal. If it were not for Punk, we may not have heard of Wire, who's influence on Post Punk is huge, or the Replacements just to name two.

Punk may have turned into something of a Fashion Over All happening media-wise (so is almost everything else if you look at it), but there are those who still hear the real deal and listen to bands new and classic.