To be honest, there’s no real need for you to contact sellers before placing the order. Sellers can’t hold that against you as Fiverr has designed their system keeping in mind that buyer like yourself would like to have a hassle-free purchasing experience: just clicks a few buttons and upload relevant files/documents and voila, your order has been placed.
However, there is a valid reasons why sellers ask buyers to contact them first before placing the order. You see, not every buyer is as shrewd as you and some buyers just do not really understand the seller’s skills/their capabilities and can end up ordering something the seller is not capable of doing.
There are some other buyers who do not even go through the entire gig description of a seller before ordering from them (which, as you can imagine, will be disastrous for both the buyer as well as the seller).
This is the reason why sellers often prefer buyers to contact them first so that they can better understand the project and let the buyer know if they are capable of working on the order.
However, since Fiverr likes to give buyers the freedom to choose whether or not they would like to contact the seller first before placing the order, Fiverr gives buyers both options. You can choose either of them. That’s the reason why Fiverr does not just remove the purchase button.
Want to be sure that you are going to get what you asked for? In my opinion, it’s better to contact the seller first.
Fiverr is not going to help make that decision for you. It is all in the buyers’ hands. Buyers have the freedom of choice.