Why might you ask? Because small companies can't afford expensive tools and need to use the out-of-the-box features as much as possible.
This past week, I rediscovered that you can alert on SQL Server performance conditions using SQL Server Agent. I needed to alert on database transaction log usage.
How to create SQL Server Agent alerts can be found at the link below.
Under Options, I suggest you set a delay of 10 minutes. Unless you like to be spammed every minute when bad things happen.
I'm hoping it will provide enough notice to prevent an undesirable event from complicating my life.