Automations can definitely control the new app’s equivalent of SHM (smart home monitor), which is STHM (SmartThings Home monitor).
The confusion is probably because “routines“ from the classic routine were mostly converted to “scenes“, and for whatever reason those cannot control STHM. 
It takes a combination of scenes and automations in the new app to match what you could do in the old routines. Again, I have no idea why they did it that way, but they did.
See the community FAQ for details:
FAQ: How to Run Scenes and Automations (2018 V3 App)
So you may find you can re-create most of what you had, but it is done a little differently. and I don’t know why they didn’t give us a guide for what the changes were and how to move forward, but again, they didn’t.