Disclaimer: If any of this sounds a bit rambly or convoluted, it's because it is 7:24 in the morning here and I have not slept well in the last few days. Read at your own risk.

I think the whole idea of authenticity is a pretentious, elitist mindset that holds pixel art (as well as most mediums) back.

The idea of authenticity has validity if you have some base level or standard to compare to. For example using a brush that looks kinda like pencil in Photoshop is not authentic pencil art, for what that's worth. As far as pixelart goes you can IMO only really go as established rulesets, which stem from hardware restriction. So you could do things like art that is authentic in the constraints regarding different machines, such as NES, C64, Amiga, and so on. All of this is totally value free IMO and everyone should be doing what they enjoy, without telling others what they are doing wrong, esp. when it comes to things like style.

There are things where people can be helped with getting better, such as art fundamentals, anatomy, lighting, colour, as well as more pixel art specific things such as aa, dither, clusters (in the sense that clusters are important in helping what you are trying to communicate, whatever that may be, for example, more noise might be something you want, so you choose smaller more noisy clusters.), colour conservation, etc. That is what this forum is for. I don't think that any of the moderators on here are part of the crowd that would advocate "pixel purism" as the one true path, unless I missed something.

I, personally, as an artist who has worked in the game industry for over a decade now, mainly doing pixelart, I do not give a fuck about purity in my work, I care about getting stuff done. What matters is that the client is happy, and if the client wants a more "pure", or a better term would be "oldschool" look, then that is what I do.

One of the reasons it took me so long to get into doing pixel art was because of that mentality. I accepted for quite a long time this false pretense that pixel art is a style, rather than a medium.

I don't think that pixelart is even a medium as such. It is a somewhat of a medium-style mix.
To say it is a medium you would have to specify what makes pixelart pixelart, and then you are at square one once again. I guess the smallest common denominator you could boil it to is "you can see the pixels"

To make the style/medium thing a bit clearer.

Digital art is a medium, in digital art you get a bunch of different approaches; 3D polygonal, 3D voxel, 2D raster, 2D vector are the ones that come to mind. Those I guess could be called actual mediums.

And at one point in time what we now call "pixelart" was the cutting edge, or the only game in town until things like early prerenders and realtime 3D, and then also higher resolutions came onto the market.

So what I am saying is that both pixelart and high definition digital illustration would fall under 2D raster art (or actually mixed medium of the 4 above, I have used 3D as guides to make pixelart before, and I am certainly not the first person to do so). Or lowpoly stuff like Quake, or even earlier games that are way more primitive, and modern stuff like Doom 2016, both utilise polygonal 3D art (which also uses 2D raster art to a huge amount for textures), but lowpoly is nowadays seeing a comeback in the indiescene and is seen as somewhat of a style. But pretty much everyone doing 3D nowadays would tell you that being able do to good lowpoly models is something that is useful, because it trains you in things like economy and developing things with strong silhouettes (which is very important for good character design).

What I am getting at ultimately is that the wordsauce and semantics do not really matter, what matters is what people do with what they are given, or what they choose to use. If that makes them, and maybe even others happy, and even better, enables people to make a living, and hopefully make their ideas come to fruition, then great, that's awesome. I am all for that.

I wouldn't have started doing pixel art if I didn't want to push the boundaries of it and modernize it.

To me the idea of modernising pixelart sounds a bit like modernising pencil drawing, or oil painting. You can of course take clues from things that were not possible 20 years ago (which is again, largely due to hardware constraints.) And if modernising means just branching out into different styles that people have not generally used much or at all in pixelart then you are not doing anything groundbreaking either, you are just applying your own artistic vision. There is a lot of aping styles going on in pixelart (art in general), and it can be very tiring, there I totally agree. But I doubt you will reinvent the wheel in terms of pixelart.

I just don't enjoy adhering to a strict template.

That is fine, and no one here will tell you to do that (unless you wanna take part in some activity that has restrictions, like the hex corpse ones). Do whatever you feel will help you grow as an artist, and if you think people on here can help you with this and you can help others in this regard as well, awesome.

Maybe it's a narcissistic part of me that needs to stand out and have a distinct style, or maybe I just don't like boring tired art that peaked 20 years ago.

That last statement is just as narrow-minded as the idea of "pixel purism". The past is here to learn from, in all regards. And there is a lot of that "boring tired art that peaked 20 years ago" that many of us will never reach, as far as level of craftsmanship goes. Ignore the past and what you can learn from it at your own peril.