Mostly it's about the maintenance costs of owning and managing a server -- on Lambda most of these tools are "set and forget".

I don't want to have to manage security updates, disk usage, or any of the other multiple things that come with owning a server.

I also could probably debate on the friendly-ness of just dumping all of these one-off services onto a single server (seems like it could get messy pretty quick), but I think you could probably go either way on that.

We are also an AWS shop for our "production" stack already, so there is no added overhead for owning an AWS account.