In Obsidian Chill's videos that are always ranked lowest on damage. And they don't move or last as long. So what is the use case for them or is it purely cosmetic?
All damage from normal pets is higher, but it's damage in 60 seconds, and turrets do all damage in 10 seconds, and although all damage is lower, but DPS is higher. Turrets are mainly used for high explosive damage (there are a couple of other situations....)...
Damage check mechanics, brutal add phases, feats for buring adds super fast, soloing applied science in Deluge CC, smacking Neron in the solo before he covers the ground in lava, etc. The list goes on… You wouldn’t really run them as your default pet in a regularly used armory. But they prove to be invaluable frequently enough to always carry a ST turret and AOE turret in your inventory.