I generally try to avoid re-inventing the wheel, and so I have avoided implementing things like presence- and time-based changes directly (as so for notification engines and weather stations). Using the Ecobee app/website to manage schedules, for example, are significantly easier for the user than trying to cobble together a decent UI on either Hubitat or SmartThings. And since both platforms offer a plethora of means to trigger things (even if only to turn on a virtual switch), I have focused instead on making it easy to drive actions on the thermostat, rather than attempting to directly implement presence or timers.
You can of course use the Hubitat thermostat scheduler, but it really dumbs-down the Ecobee, preventing use of many of its advanced features (Smart Recovery, follow-me, auto-away, etc.). For me, when I pay over $200 a thermostat (for 7 of them at this point), I really don't want to turn them into HA versions of the old Honeywell wall puck .
For me, ease of use in Home Automation is about connecting triggers into actions, so when I leave my house I want the doors to lock, lights & home entertainment to turn off, alarm monitoring turned on, and the temperature set back. The only thing I let my thermostat drive is Vacations: I schedule them on the Ecobee, and when it/they change to Vacation Mode (program), they also tell my house to go into Vacation mode. Other than that, my Ecobees are just another appliance to be automated...
I hope you enjoy the Ecobee Suite - lots of neat stuff that you can do with it, much of which has been driven by other users.