They're not the problem - a few months here and there isn't an issue. The problem ones are the ones left empty for several years if not decades. Often due to the owner being in a care home and in not fit state to deal with selling the home - the council get a legal charge on the house to cover the care home fees they are having to pay.
We've had one on our small road - we moved in 29 years ago and it was clearly unoccupied back then - over the years/decades it got more and more decayed and was finally sold at auction around 3 years ago and the new owners had to do a complete refurb job that took a year. So at least 26 years empty. Apparently, talking to neighbours, she died in her care home about 10 years ago, but the council didn't seem to be in any rush to deal with the house sale.
Another was a friend of my late mother who had no family. She went into a care home in 2010, and her house is still unoccupied and getting more and more derelict. She is still in the care home, 16 years later. That's 16 years of her house being empty and unused, again going rotten.
Same in our "High Streets". Lots of empty/derelict flats above empty/derelict shops. Often because the council won't grant planning permission for change of use back to residential as often the "flats" above were converted into storage etc when the High Street was booming, so no longer have "dwelling" planning permission. Councils often include entire roads/areas in their local plan as "commercial" so automatically reject planning applications to convert back into residential.
Councils need to get a grip. In a lot of cases, they have the power. There's just no urgency to deal with unoccupied properties and in the case of town centres, they're obsessed with "big plans" for developments which take decades to happen, but more often than not, never happen.