Your WordPress site is not one piece of software. You have a theme laid over the WordPress core. The theme is a separate piece of software. You have multiple plugins adding functionality. Each plugin is even more software.
Without a webmaster, it’s up to you to keep the whole thing up to date. That might not seem like a big deal today. Today, your site is working, and everything is in harmony.
So why retain someone to look after what ain’t broke?
Because it will break!
There is simply too much going on in the engine room and the maths is 100% against you unless you want to become an expert in WordPress.
As experts in WordPress ourselves, we think that’s a wonderful thing to be, but our clients don’t have time. They rely on us to monitor their security and to update their sites forensically. We also take daily backups and store them securely, so even if something does happen, it would be a blip, not a wipeout.
All of this allows our clients to work on their sites confidently, adding content and making changes, because they know there is a safety net in place.