It’s not extreme, that’s the basic concept for IFTTT, that it can be used to connect two otherwise incompatible systems as long as each has their own IFTTT channel/service. 
There are two main issues that people run into:
One) additional lag. The amount of lag varies from house to house and channel to channel. At my house it’s a pretty consistent eight seconds, which works well for most things, but is too slow, for example, for a motion sensor On one platform to trigger a light coming on on the other platform as you walk into the room.
- Limited available features. With SmartThings you can often get around this by using a virtual device to then trigger routines or smart apps, but many other systems don’t allow that. So you just have to look and see what is exposed. For example, Logitech Harmony will not let you lock or unlock door locks through IFTTT, as a security measure. And Lutron Caseta Will let you use their light switch as a “that” but not as an “if.” So you just have to look at the channel/service for each platform that you are interested in to see what it can do.
If you’d like to see how some other community members are using IFTTT, see: