Genres and classifications in music, any thoughts (see details)?

So, I've been thinking a bit about genres and classifications in music lately (I know it's silly, but bear with me, I'm a weird dude). I've been thinking about how as much as I follow music I don't know the difference between New Wave and Post Punk. Where does one end and the other begin? Are... show more So, I've been thinking a bit about genres and classifications in music lately (I know it's silly, but bear with me, I'm a weird dude). I've been thinking about how as much as I follow music I don't know the difference between New Wave and Post Punk. Where does one end and the other begin? Are the two genres drawing from the same wells? This can also apply to multiple genres. I've noticed that no one can agree on what is punk rock, what is emo, is indie a label status or a sound, what is MCR (as an example) because not even their fans seem to agree. All these little ambiguities. A lot of it is generational I imagine. People of many different ages bringing different definitions and experiences to the same conversation. Sometimes I think that the whole thing is so undefined that it is not at all effective. It almost seems like there should either be a clear reference point or the whole thing should be just totally blown up.

So, in a nutshell, what are your thoughts on genres.
Update: Or, any thoughts on any of the specific portions of the question. I know that was pretty much just vomiting different thought processes, but I'm just curious if anyone else has had similar thoughts or opinins on the subject in general. Curiosities of your own. I'm taking off for the day, but I look... show more Or, any thoughts on any of the specific portions of the question.

I know that was pretty much just vomiting different thought processes, but I'm just curious if anyone else has had similar thoughts or opinins on the subject in general. Curiosities of your own.

I'm taking off for the day, but I look forward to reading into the answers tomorrow and responding to what I can.

Have a great night.
Update 2: Thanks so much for chiming in. There are some fantastic answers in here. I've got to get to work so I don't really have time to respond to all of them, but really, really great work everybody.
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