I say the local government gets eminent domain on any properties that aren’t primary residences staying vacant more than a year and/or vacant >75% of the time over 5 years. Make it the owners responsibility to keep someone living under the roof. There will be enough loopholes that it won’t be their second home, by maybe by the third and any corporately owned ones they’ll start to sweat.

Since you seem to be stubborn and unwilling to accept friendly advice, here’s a wikipedia article on why It’s a problem

https://www.wikipedia.org/wiki/Fatberg

That’s pretty much everywhere