My own .02 or two cents is a bit on the eclectic side.
First and foremost, though I've been taking (and trying to take) photographs for decades and decades, there's no question, in my own mind, at least, of what kind of a 'photographer' I am: I am definitely an amateur. Probably a rank amateur as well, depending on one's definitions (of both the word 'rank' and the word 'amateur'). I've always been fascinated by the process of trying to take pictures - and the related processes of trying to either a) see what I have taken, or b) modify what I have taken in some way or ways that somehow make sense to me at the time. Garry Winogrand's quote - "
I photograph to find out what something will look like photographed" - has really become something of a mantra for me. But...
What does all that have to do with cropping, or not cropping? Nothing and everything. For me, it's all personal and subjective and related to how I might be feeling on any given day, week, month or year. BUT... for quite a few years (and decades even) I was entranced by the philosophy, or ethos, of trying to never ever crop any of my photos. Because, or so the theory went, there (supposedly!) is (or might be) some intrinsic value in your photo as a document of a sliver of a fraction of a moment in time - and (somehow, I can't remember how) there was supposedly a value in just preserving that moment, or that image, exactly as it was at the moment you press the shutter. There used to be a whole movement about the supposed or perceived 'value' of printing your 35mm image in such a way that it included the frame lines of the film just beyond the negative - as some sort of existential proof that you hadn't altered that one moment you were documenting. (Ironically, I think this movement was also related to another, seemingly inimical photography philosophy, having to do with the perceived purity of 'snapshots' - literally moments just 'snapped' or frozen out of time.)
Thinking about it all reminds me of the occasional mad passions of young undergraduates debating weighty questions of philosophy, of literature, of art, of life, trying to find the 'meaning' or 'purpose' hidden in them. There was definitely some of that in my (relatively mindless) attempts to shoot just the full frame and never, ever crop. And, of course, if you allow yourself to 'believe in' some of that, it can be... immensely entertaining (from a certain perspective, at least). (And, confession follows, I used to be one of those mad, irrationally passionate undergraduates myself, once upon a time... so I can relate.)
Now, after still more years and decades of taking photographs, I've allowed myself to evolve or mature or (pick the verb of your choice) to explore and often embrace the possibilities of cropping my images. For about a million different reasons, which tend to vary from photo to photo.(And definitely including the reason Chris -
@MountainMan79 - mentioned, about wildlife photographers needing to crop. Most of my images or photos of birds or animals or insects tend to improve radically with some cropping. Although, strangely, some don't. But that's another kettle of metaphorical fish...) So...
Long story short, cropping has become part of the (always surprising) magic of photography for me. But, paradoxically (old habits die hard), there are times when the ethos or notion of preserving a photo exactly as it was (framing, lighting, whatever) at the moment I pressed the shutter... also resonates for me. I'm full of contradictions - which, coming round full circle, is one of the cool things about just being an 'amateur' photographer. Allowing myself the freedom to try or do things that appeal to me, without having the onus of needing to shoot or develop or print something 'the right way' for my client or boss. And, coming back to Peter's (
@Petach) original and thought-provoking first post, about the need (or lack thereof) of megapixels... well, I'm all over the map on that one. Part of me doesn't care about the relationship between megapixels and so-called image quality, before or after cropping. It's a non-issue. But also, either paradoxically or perversely (or pick the adverb of your choice), I've got to admit that the resolution of certain images I've taken with newer, higher resolution cameras (specifically my Pentax KP and my Fuji X-T5) inhabit such a different universe than those I took years ago with my old small-sensored Olympus C-8080 (or those I still take with its smaller sibling, the C-7070) that... it's a lot more fun and rewarding to crop digital negatives from the newer ones. Which is basically what Matt (
@MoonMind) was saying.
Short version of the preceding: it can be fun and rewarding, to be both a rank amateur - and occasionally 'just lazy'. (But. if I had to make my living from my photography, I might repudiate everything I've just said

...)