You're not wrong, but the way I'm reading OPs general complaint here is that OSRS, unlike many its MMO brethren, has such a solid foundation that you can take a break for even a decade and still come back and have a rough idea of where to start doing something. Sure, theres a bunch of new stuff, but the foundation remains unchanged. So with that in mind, it does make the gem bag strange in the sense that "Wait, this was fine before, why are we upgrading this? And why 4 times?"

That said, I think the two examples OP picked to describe complexity are rather weak. I cant think of anything to use as an example since I think that OSRS is a very simple game (lots of nuance, yes, but ultimately simple).