I would, but two things first.

1. I keep doing so.

2. You claim otherwise.

No point.

Once more then.

Folk is folk. It includes traditional folk, contemporary folk, folk rock, folk baroque (special sub genre for Pentangle presumably) and many other sub genres such as protest, roots, world, singer / songwriter, celtic etc.

All the above can slip between genres because the 1954 and any other attempt at defining something which is abstract and entertainment is sheer folly.

Folk is an umbrella term, and to get back to the original question;

Yes, you can write a folk song. If Jim Carroll says you can't, it isn't a problem because he isn't important.