Version exclusives have always been a terrible but impactful design choice. It's an understatement to say I don't have a very complete memory of my childhood, but I do remember discovering version exlusivity as a concept in a Pokémon Magazine during the pre-release of HGSS. I had played other mons games before that, but the concept of version exclusivity never occurred to me because I had never tried to complete the dex.
Specifically I remember struggling to decide between Phanpy and Teddiursa. These were two of my favourite Pokémon at the time, hell they still are I have a Phanpy plushy on my desk below the monitor I'm writing this on and an Ursaring in my profile picture, and I spent real emotional energy determining which of the two I liked more to choose which version I wanted to get.
And then the decision doesn't mean anything because they're extremely underlevelled in an optional endgame area at a 10% encounter rate. I didn't know where to catch them, I just knew they were version exclusives, and by the time I got to Blackthorn City I'd already forgotten that Phanpy was the reason I chose HeartGold in the first place. Which is a good thing, because otherwise I would've been trawling the map constantly to try and find it which would've annoyed the hell outta me.