Is it not possible to offer free shipping with an individual seller account?

Im an FBM seller, i posted a product I have under an already existing listing. When i go to the listing and click the other buying options it shows my product and a $4.99 delivery fee. Id like to make this zero and offer free shipping, saw some other posts that say i cant make this zero. Whats the reasoning for this? Obviously this makes it less appealing to the buyer. Is it a way for them to force you to buy the professional seller subscription? Thank you.