Cost. But I do not agree with 'Whi would i pay for a service when i could host it myself for free?'
It is not 'free' it is cheaper. Today I got a quote from utilities company saying that api access to how much heat I use is 20 EUR/month a software defined radio recover is 20-40 USD + shipping. To do a full setup and research it takes about half of day some exiting HW and electricity but even summing all of that up. It is cheaper and utils company has already lied to me at least twice this year, so... their stacking motivation for me to independetly monitor the metering.