The value-add here is not to be running cloud instances in containers. Rather it allows you to run containers and be billed by the second, which opens the doors to short-lived jobs running in containers on the cloud. It's closer to serverless platforms rather than VMs.

I built an internal tool where teammates submit some details and a fairly computationally heavy data processing task run and posts the summarised results back to a slack channel.

I use containers for this, because it's a really easy way to really quickly get access to compute instances (which vary in size from like 4gb ram to 100gb+ of ram depending on what the user submitted) really quickly and for really cheaply because I only pay for the time it actually runs, rather than renting out an EC2/VM instance all the time (which would either be underpowered, or end up costing too much), or build some frankenstein-ian thing to dynamically provision and spin up EC2 instances on demand, set them up and then shut them down/terminate them once they finish.