You know your app better than me, but here are some practical reasons for the typical B2C app:

split deployments -- perhaps you want to see how an update impacts something: if error rates change, if conversion rates change, w/e. K8s makes this pretty easy to do via something like a canary or blue green deployment. Likewise, if you need to rollback, you can do this easily as well from a known good image.

Perhaps you need multiple servers -- not for scale -- but to be closer to your users geographically. 1 server in each of -5-10 AZs makes the updates a bit more complicated, especially if you need to do something like a db schema update.

Perhaps your traffic is lumpy and peaks during specific times of the year. Instead of provisioning a bigger VM during these times, your would prefer to scale horizontally automatically. Likewise, depending on the predictable-ness of the distribution of traffic, running a larger machine all the time might be very expensive for only the occasional burst of traffic.

To be very clear, you can do all of this without k8s. The question is, is it easier to do it with or without? IMO, it is a personal decision, and k8s makes a lot of sense to me. If it doesn't make a ton of sense for your app, don't use it.