Yes. Kinda, depends what’s doing the triggering.
That’s not intended functionality, it’s an example of snapshotting that the devs want to get rid of.
As I understand it, the thing doing the triggering is the thing “doing the work” so it needs to be equipped (either on the skill bar or on your character if its an item). So if you’re using the Smite on throwing hit idols to proc Smite, they need to be on your character to proc Smite but Smite doesn’t need to be on your bar. If a skill is proccing itself, such as Sigils of Hope with the on kill node or Summon Volatile Zombies with the summon on kill node, thpse skills are what’s doing the summoning so the need to be on your skill bar.
Because its the minion skill that’s doi g the summoning so you need to keep it on your bar for it to work.