A little true, it depends on the Pokémon and situation. If it's one of the neutral natures like serious then I would probably actually use it for a casual, in-game playthrough, since it's not competive or a battle facility. If it's a nature that really hinders the Pokemon though, then I wouldn't use it for any battles, but that doesn't necessarily mean I would straight up box the Pokemon, if it had a really bad nature but could be a designated hm user for me, or had an ability or move that does something in the overworld, then I would let it travel with me sometimes. When I receive abras or female ralts on wonder trade with natures like adamant they sometimes end up being synchronizers for me. That being said, there are definitely times where I would just box or wonder trade a Pokemon.
Tpbm has seen a starter Pokemon and loved the design of it's first form, only to be disappointed with how it's evolution changes.