You’re both saying the same thing. It’s an issue that bothers some people and doesn’t bother others.
Say that before you put the relay in when the switch was up the light was on and when the switch was down the light was off.
Now you put in the relay. If you only use the physical switch it would work exactly the same way up would be on, then flipping it to down would be off.
However, say the switch is in the down position and the light is off. Now you tap the icon in the SmartThings mobile app to turn the light on. The light comes on, but the switch is still in the down position. So the next time, if you want to turn it off from the wall switch, you have to flip the switch up.
As @rxsamg points out, it is possible to wire a nonnetworked three-way set up so the same thing happens. Sometimes you flip the switch up to turn the light on, sometimes you flip the switch down to turn the light on, it depends on the position of the other switch on the three-way. Again, that bothers some people and doesn’t bother others.
If it doesn’t bother you, you’re fine using any traditional non-network switch with the micro.
However, if it does bother you, the simplest solution is to use a momentary switch instead. It just makes it more intuitive for guests, and again, to some people it’s just aesthetically more satisfying than a switch which could be going in either direction for an “on.”