Most sites are lost to something mundane: a bad plugin update, a botched edit, a failed migration. Hosting backups are a safety net for the host, not a restore plan for you. A dedicated backup service means you can roll back to yesterday in minutes.
Host-level backups usually exist for disaster recovery across the whole platform, not for restoring one customer site to a specific hour. They can be slow to request, limited in retention, and stored on the same infrastructure as the site. If a plugin update breaks your checkout on a Friday afternoon, you want a restore point you control.
Backups get you back online after something goes wrong. Website security stops most of those incidents happening in the first place, and SSL encrypts traffic in transit. Most business sites need all three.
Daily for most sites. If you take orders or publish frequently, hourly is worth the difference, because a day of lost orders costs more than the plan does.
Usually minutes. The slow part is deciding which restore point you want, which is why browsable history matters.
Yes. Website security prevents most incidents; backup covers everything else.