It's becoming more and more common particularly right now when the business is slow for connies and even people that had been in full time permie work until recently. I know a couple of guys who have done just that.
Yes, you need the practical experience to get the type rating on your licence but having the course certificate will get you a foot in the door for a permie position for that type before somebody without the course cert if the employer can't get somebody suitable already type rated and is prepared to take you on to get the required experience.
You could look at it another way - most companies apply a training bond
on you when they send you on a course (I'm talking permies here) so as a permie you end up paying for your course in a way whether hard cash if you leave or loyalty / retention if you stay.