This will also allow you to connect your different devices that are tied to a specific vendor. For example, you can run your arlo camera, eufy robovac, google nest fire detectors, honeywell smart thermostat, Hue smart bulbs, Amazon smart plugs, etc to this open source controller. So you don't have 100 different apps on your phone and have google assistant for your nest and Alexa for your smart plugs and whatever the fuck for your ORBI, etc. And like
@dasailr03 said gives you the power of granularity.
Before someone comes in and says I can control my eufy with my Alexa .... yes there is some cross compatility but not every smart device allows control from every major controller. This open source solution that OP is talking about doesn't have any limits. I haven't used it but anyone with the right skills can connect anything to it.
Just to be clear. I haven't used it and my answer is based on what I read so far.