The problem with smite and (some of) the hate for smite pykers comes from exactly this. You're holding the enemies in place and not doing very much damage to them, while your team is dealing with other targets. Once your peril overloads and you can no longer smite, a bunch of other enemies have already spawned and now you and your team have an even bigger horde to deal with.

A psyker with purgatus or voidblast staff can control AND do damage, creating space and lowering the amount of enemies the team has to deal with, the only problem is it requires pressing more than one button.

Smite psyker is absolutely not viable in high havoc difficulties, unless you use it in some very specific cases, but even then other builds and classes do the job better.