To give her her due, she does deserve a lot of credit for getting them going, on two fronts.
Firstly, the lads were clueless on how to make a podcast when they started it-they freely admit this. Maura was on board from Day 1 , and if you remember, the podcast went straight to no 1 immediately, there was no slow burn. She has to get credit for that.
The other thing is that she got them on the Late Late very early in their careers (she used to be a researcher with the Late Late). That would have done them a great boost in terms of exposure.
I dare say she is far from indispensable now. They now have Neil on board (who seems to take care of all the recording and technical stuff) and Katie Jane who does the research (and also is a radio presenter in her own right). However, I don't think the lads would throw someone off the ship who was so vital to getting them up and going.