In many ways Kanto feels like it's own self-contained series separated from the rest of the anime, (even Orange Islands and Johto), because it was just intended to be a one and done thing. A lot of casual fans who never watched much of the anime after the early seasons largely just think of Kanto, even if they watched parts of Johto they probably don't even remember most of it. That's why there's not much nostalgia for Bayleef/Cyndaquil/Totodile, etc. as Ash's original Kanto team, you virtually never see that same type of nostalgia extended to the Johto segment.
I remember Ash leaving Charizard in the valley was a breaking point in 2001 for a lot of original fans for a few reasons:
1. Back then we had no idea if Charizard would come back, Charizard seemed like he was released similar to Pidgeot. Keep in mind back then most fans also weren't on the internet and didn't look up new episodes, so back then people assumed Charizard would be gone for good.
2. People simply assumed Charizard would remain on Ash's team forever. Like back then there was no indication Ash would constantly swap out old pokemon for new ones.
3. The initial fad of pokemon largely died up after the first year of Johto, hence many kids generally losing interest
Obviously looking back at this now, none of this matters anymore. But if you go back to the context of 2001 before we knew the anime would go on for 20+ years, it had a big impact. Probably the same people who tried to make a big deal out of Misty leaving felt the same, even though as said looking back on it now 16 years later, it made no difference.
I remember Ash leaving Charizard in the valley was a breaking point in 2001 for a lot of original fans for a few reasons:
1. Back then we had no idea if Charizard would come back, Charizard seemed like he was released similar to Pidgeot. Keep in mind back then most fans also weren't on the internet and didn't look up new episodes, so back then people assumed Charizard would be gone for good.
2. People simply assumed Charizard would remain on Ash's team forever. Like back then there was no indication Ash would constantly swap out old pokemon for new ones.
3. The initial fad of pokemon largely died up after the first year of Johto, hence many kids generally losing interest
Obviously looking back at this now, none of this matters anymore. But if you go back to the context of 2001 before we knew the anime would go on for 20+ years, it had a big impact. Probably the same people who tried to make a big deal out of Misty leaving felt the same, even though as said looking back on it now 16 years later, it made no difference.