>>31831586It's a Stall Pokemon that came out when Stall was universally hated due to overcentralizing the metagame (Gen II). It was the next best thing if you didn't/couldn't use Blissey, since due to being a starter it was VERY easy to acquire compared to Chansey.
Gen III onwards, power creep allowed many Pokemon to do its job but better. Doesn't help that Grass is a shittier defensive type than it used to be due to Flying and Bug getting so many powerful moves. Even though it dropped in usage to the point of never being seen in competitive again, the bad taste still lingered to the point where most people hate it for the sake of hating it because they forgot what it was originally hated for.
People still hate Blissey for the same reasons, which is noticeable because Blissey is still competitively relevant.It's not good competitively, but hating it is a meme. I personally love its design.