I would avoid self-hosting backups at the same location where your devices are currently kept. There is a reason off-site backups are a thing. So many failure causes are shared with devices in the same home, from electrical issues (lightning and technical defects among other things) over water and fire damage to theft.
That being said: backing up to a single, central, local location and then syncing those backups to some offsite location can actually be very efficient (and avoids having to spread the credentials for whatever off-site storage you use to multiple devices).
I’d say it’s about designing a good strategy. I have local backups on my NAS and a nightly incremental backup to cloud locations from there. That way the capture from my local equipment to the NAS is lightning fast and it’s not a big deal to have it take a few hours to reach the cloud. Also having a NAS on a power backup is a must-have.