people consider them pests because they breed quiet readily with available food and the babies are small enough to go up into the filter which i guess can cause some issues. if you want to limit numbers of snails, limit how much uneaten food is in the tank.
otherwise they can be useful for eating dead plant matter and most types of algae (i don't think they eat hair algae though)
honestly i think it's fun to watch snails, even if they end up everywhere
Djura: Red Crowntail
Logarius: Blue-black/Orange Crowntail
School of Mensis: School of White Cloud Mountain Minnows
Shadows of Yharnam: Oto Catfish
The Church: Ghost Shrimp