It is possible to simulate this with built-in functionality by using the Default Values dialog to pre-populate the table with a lot of rows and then conditionally hiding as many as you need to. However, this is clunky because it gives you a whole bunch of empty rows and limits the number you can use.
Actually adding rows dynamically is not possible with built-in functionality, but it is extremely easy if you use qRules. Would that be a possibility for you?