Ask HN: Are managed DB so important?

In the past I've been deploying everything (application + DB) in the same server for small projects. I didn't have the need to split the DB into another server, but I think it wouldn't be a big issue.

The think is that I will start something that I hope it will become a SME -I know for sure it won't be Internet Scale-, but people tell that using a managed database is a must.

My question is:

Given that I am already proficient with Linux, and my cloud service makes automatic snapshots (besides other rsync backup I do), Is it really such a big deal?