Isn't the alternative that they find a SaaS company to do it for them? Everything from WordPress to GitLab to Jenkins to ELK has good we'll-run-it-for-you vendors. (Bitnami also offers things like memcached and kube-state-metrics and language runtimes, but I'm not sure how you manage to make sure of them without having enough expertise to install software yourself. You can definitely find vendors to do the higher-level task for you, if you're in the market for something like that.)
Or that they hire someone with the relevant expertise, but sure, we can assume that they're not going to do that for the purposes of discussion.
Sometimes that is possible but not always. Sometimes it's cost prohibitive for a small use-case like a small business or an instance just a particular team. Sometimes those vendors want long-term contracts. Sometimes the providers themselves are not that great. You would be surprised how much revenue a nice front-end for creation with no operation support can bring (e.g old-school LAMP hosts).
As someone currently running a bitnami wordpress site on aws it's pretty nice being able to SSH in and change whatever you want. Bitnami gives you a reasonable starting point but then you have a lot of flexibility over how you manage the server. Maybe installing everything yourself isn't too hard, but I only run the website because I happen to be the most technically competent person around so it's nice not to have to think about it.
Admittedly I've only tried one managed wordpress service, but it was total garbage in comparison. Debugging basically involved opening a support request because even the most basic tools weren't available.
Not in the hypothetical world where Bitnami reaches through the connection and manages the “server” embedded in the software for them. Like Ubuntu LTS with automatic security updates + kernel patches turned on, but at the individual-application level.